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Full text of "A system of anatomy for the use of students of medicine (Volume 2)"

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SYSTEM OF ANATOMY 

FOR THE USE OF 

STUDENTS OF MEDICINE. 

BY CASPAR WISTAR, M.D. 

LATE PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA. 

WITH NOTES AND ADDITIONS, 
BY WILLIAM E. HORNER, M.D. 

PROFESSOR OF ANATOMY IN THE UNIVERSITY OF PENNSYLVANIA. 

SEVENTH EDITION. 

ENTIRELY REMODELED AND ILLUSTRATED BY NUMEROUS ENGRAVINGS. 

BY J. PANCOAST, M.D. 

LECTURER ON ANATOMY AND SURGERY, ONE OF THE SURGEONS OF THE 

PHILADELPHIA HOSPITAL, FELLOW OF THE PHILADELPHIA 

COLLEGE OF PHYSICIANS, ETC. 

IN TWO VOLUMES. 
VOL. II. 

PHILADELPHIA: 

THOMAS, COWPERTHWAIT & CO. 
1839. 



as 



IHntereti, according to the Act of Congress, in the year 1838, by Thomas, 
Cowperthwait & Co., in the Clerk's Office of the District Court of the 
Eastern District of Pennsylvania. 



: 






CONTENTS OF VOL. II 



PART VII. 

OF THE ABDOMEN. 
CHAPTER I. 

GENERAL VIEW OF THE ABDOMEN AND PELVIS, AND THEIR CONTENTS. 
GENERAL ANATOMY OF THE SEROOS TISSUES. OF THE PERITONEUM. 

Of the Abdomen, - - - - - 14 

Regions of the Abdomen, - - - - 15 

Pelvic Viscera, ... - - - 16 

Explanation of Plate of Viscera, - - - - 20 

General Anatomy of Serous Membranes, - - 21 

Of the Peritoneum, - - - - - -24 

CHAPTER II. 

GENERAL STRUCTURE OF THE ALIMENTARY CANAL. OF THE OESOPHAGUS, 
STOMACH, INTESTINES, ETC. / 

General Structure, ..... 29 

Of the (Esophagus, - . - - - - - 30 

Stomach, ..... 33 

Intestines, ------ 42 

Villous Coat of, 43 

Villi of, - - - - 44 

Division of, 46 

Small Intestines, - - - - - 47 

Duodenum, - - - - - - 48 

Jejunum and Ileum, ----- 49 

Great Intestines, ----- 53 

Ccecum, - - - - - -'53 

Colon, ------ 54 

Rectum, - - - - - - 57 

Absorbents and Nerves of Intestines, - - 60 

Omentum, ------ 60 

1* 



<\\j> 



'A1 



07 

68 



VI CONTENTS. 

Of the General Anatomy of Mucous Membranes, - 62 

Villi, - ,.„ 
Blood-Vessels and Nerves of Mucous Membranes, 
Absorbent Vessels, - - - - 
Follicles and Glands, 
Lieberkiihn's Follicles, - 

Glandulae Solitariae, - *~ 

Glandulae Agminatae, - * A 

General Anatomy of Glandular Tissue, - - 75 

Capillary Blood-Vessels of Glands, - - - 81 

CHAPTER III. 

OP THE LIVER, PANCREAS, AND SPLEEN. 

Of the Liver, ------ 84 

Lobes of the Liver, - - - - - 85 

Ligaments of the Liver, - 86 

Hepatic Vessels, - 88 

Hepatic Duct, ----- 90 

Hepatic Nerves, - - - - - 91 

Acini of the Liver, .... 92 

Pancreas, - - - - - - 100 

Spleen, ------ 103 

CHAPTER IV. 

OP THE URINARY ORGANS AND GLANDULE RENALES. 

Of the Glandulae Renales, - - - - 112 

Kidneys, - - - - - -114 

Ureters, - - - - - - 121 

Urinary Bladder, - - - - - 123 

Sphincter of the Bladder, - - - 125 

CHAPTER V. 

OP THE MALE ORGANS OP GENERATION. 

Of the Testicles and their Appendages, - - - 132 

Scrotum, - - . . . -133 

Dartos, - - . . . . 134 

Spermatic Cord, - . . . - 1 35 

Tunica Vaginalis Testis, - - - 138 

Tunica Albuginea, - - . . - 139 

Epididymis, - . . . . 139 

Body of the Testicle, - . . - 140 

Ducts of Testicle, - . . . 142 



CONTENTS. VII 

Of the Vas Deferens, - - - - 143 

Vesiculae Seminales, - - - - 144 

Prostate Gland, - ' - - - 146 

Covvper's Glands, - - - - - 148 

Of the Penis, - - - - - - 149 

Corpora Cavernosa, - - - - 1 50 

Urethra, - - - - - - 152 

Canal of the Urethra, - - - - 153 

Integuments of the Penis, - - - - 159 

Fascia of the Perineum, - - - - 161 

General Anatomy of Erectile Tissue, - - 163 

CHAPTER VI. 

OF THE FEMALE ORGANS OF GENERATION. 

Of the External Parts of Generation, - - - 167 

Vaginae, - - - - - - 171 

Uterus, - - - - - - 172 

Fallopian Tubes, ..... 176 

Round Ligaments, - - - - 178 

Ovaries, - - - - - -178 

Vessels of Uterus, - - - - 180 

Bladder and Urethra, - - - - 181 

Changes induced in the Uterus by Pregnancy, - 183 
Abdomen of the Foetus, .... 185 

Umbilical Vessels, - - - - 187 



PART VIII. 

GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 
CHAPTER VII. 

BLOOD-VESSELS IN GENERAL. GENERAL ANATOMY OF THE ARTERIAL 
SYSTEM. OF THE HEART. OF THE VENOUS SYSTEM. 

Of the Blood-Vessels in general, - - - 190 

General Anatomy of the Arterial System, - -192 

Structure of the Arteries, - - - 193 

Position of the Heart, - - - 199 

Dimensions of the Heart, - - - 199 

Form of the Arteries, .... 203 

Capillaries, ..... 205 

Action of the Heart and Arteries, - - - 208 



212 
213 
214 
215 



viii CONTENTS. 

Of the Pulse, - 21 q 

Veins, - 

Blood, - - 

Serum, 

Crassamentum, - 

Colouring Matter, 

Globules of Blood, - - - - *JJ 

Globules of Chyle, - - - ■ - 2 IS 

CHAPTER VIII. 

DISTRIBUTION OF THE ARTERIES. 

Of the Aorta and its Branches, - 220 

Common Carotid, ... - - 222 

External Carotid and its Branches, - - 223 

Explanation of Plate of the Distribution of the Branches, - 233 

Of the Internal Carotid and its Branches, - - 235 

Subclavian and its Branches, ... 239 

Explanation of Plate of the Arteries of the Brain, - 242 

Of the Axillary and its Branches, . - - - 245 

Explanation of Plate of the Arteries of the Arm, - 252 

Of the Branches sent off from the Aorta below its Arch, - 255 

In the Cavity of the Thorax, - - 255 

In the Cavity of the Abdomen, - - 257 

Explanation of Plate, .... - 257 

The Primitive Iliacs, .... - 265 

Explanation of Plate of the Arteries of the Lower Extremity, 265 

Of the Internal Iliac and its Branches, ... 266 

External Iliac and its Branches, ... 270 

Femoral Artery and its Branches, - - 272 

Popliteal and its Branches, .... 274 

Explanation of Plate of the Arteries of the Lower Extremities, 278 

CHAPTER IX. 

OF THE PARTICULAR DISTRIBUTION OF THE VEINS. 

Of the Particular Distribution of the Veins, - - 281 

Coronary Veins of the Heart, - - - 282 

Superior Cava, - 283 

Vena Azygos, - 283 

Intercostal Veins, .... 285 

Internal Jugular, - 286 

Externa] Jugular, - 288 

Veins of the Arm, - 289 

Inferior Vena Cava, and the Veins connected with it, 291 

Veins of the Lower Extremity, - . . 295 

Pulmonary Arteries and Veins, - . . 297 



CONTENTS. IX 

PART IX. 

GENERAL ANATOMY OF THE ABSORBENT SYSTEM. 

General Anatomy of the Absorbent System, - - 300 

Comparison between Absorbents and Veins, - - 301 

Origin of Absorbents, ..... 304 

Termination of Absorbents, - - - 313 

Of the Chyle, ...... 314 

Lymph, - - - - - - 316 

Comparison between Chyle and Lymph, - - 317 

CHAPTER X. 

ABSORBENTS OF THE LOWER EXTREMITIES, ABDOMEN AND THORAX. 

Of the Absorbents of the Lower Extremities, - - 318 

Absorbents of the Abdomen and Thorax, - - 322 

Thoracic Duct, - - - - - 328 

CHAPTER XL 

ABSORBENTS OF THE HEAD AND NECK, UPPER EXTREMITIES, AND UPPER 
PART OF THE TRUNK OF THE BODY. 

Of the Absorbents of the Head and Neck, - - 330 

Absorbents of the Arm and upper part of the Trunk, 331 

Brachio-Cephalic Trunk, .... 335 

Explanation of Plate of Absorbents, - - - 338 



PART X. 

OF THE BRAIN AND SPINAL MARROW— OF THE EYE AND THE EAR. 
CHAPTER XII. 

OF THE BRAIN, 

Of the Membranes of the Brain, - - 340 

Cerebrum, ...... 345 

Cerebellum, ..... 353 

Basis of the Brain, and Nerves which proceed from it, 354 



X CONTENTS. 

CHAPTER XIII. 

OF THE SPINAL MARROW. 

359 

Of the Spinal Marrow, - _ g60 

Ligamentum Denticulatum, - „g^ 
Vessels of Spinal Marrow, 

CHAPTER XIV. 

OF THE EYE. 

Of the parts auxiliary to the Eye, - - *"* 
Palpebral, - 

Lachrymal Gland, " " " " q?n 

Lachrymal Sac and Duct, - *™ 

Tensor Tarsi, ----- «J* 

Ball of the Eye, - - - - " «If 
Sclerotica, "'"""£! 

Cornea, gj 

Choroid, d7y 

Iris, 384 

Ciliary Body and Ciliary Processes, - - 390 

Retina, .--'--- 393 

Spot of Sommering, ... - 396 

Tunica Jacobi, ...--- 399 

Vitreous Humour, . . - 400 

Crystalline Humour or Lens, - - - 403 

Aqueous Humour, .... 408 

CHAPTER XV. 

OF THE EAR. 

Of the External Ear, - - - - - 412 

Cavity of the Tympanum, - - - - 416 

Membrana Tympani, - - - - 419 

Eustachian Tube, .... - 420 

Mastoid Cells, ----- 422 

Bones of the Ear, - - - - - 423 

Muscles of the Bones of the Ear, - - 425 

Chorda Tympani, ----- 426 

Labyrinth, ..... 428 

Vestibule, ...... 429 

Cochlea, ...... 429 

Semicircular Canals, - - - - - 431 

Contents of the Labyrinth, - - - 432 



CONTENTS. 



Jacobson's Nervous Anastomosis, 
The Aqueduct, - 
Explanation of Plate, 



XI 

438 
441 
444 



PART XL 

OF THE NERVES. 



Structure of the Nerves, 


- 


- 


446 


Nerves of the Brain, 


- 




- 449 


First pair, 


- 


- 


450 


Second pair, 


- 




- 450 


Third pair, 


- 


- 


451 


Fourth pair, 


- 




- 452 


Fifth pair, 


- 


- 


452 


Sixth pair, 


- 




- 458 


Seventh pair, 


- 


- 


458 


Eighth pair, 


-. 




- 460 


Ninth pair, 


- 


- 


465 


Of the Cervical Nerves, 


- 




- 466 


Nerves of the Diaphragm, 


- 


- 


468 


Brachial Plexus, 


- 




- 469 


Nerves of the Arm, 


- 


- 


470 


Dorsal Nerves, 


- 




- 473 


Lumbar Nerves, 


- 


- 


474 


Sacral Nerves, 


- 


- 


- 477 


Nerves of the Lower Extremity, 


- 


478 


Great Sympathetic Nerve, 


- 


- 


- 481 


Cardiac Nerves, - 


- 


- 


484 


Splanchnic Nerves, - 


- 


- 


- 486 


Solar Plexus, 


- 


- 


486 


Explanation of Plate of the Organs 


of Generation, etc. 


- 489 



CHAPTER XVI. 

GENERAL ANATOMY OP THE NERVOUS SYSTEM. 

Of the Cineritious Neurine, - - - - 491 

Medullary Neurine, ----- 493 

Neurilema, ----- 495 

Functional Divisions of Nervous Substance, - - 496 

Ganglia, ------ 499 

Commissures, .... - 499 

Nerves, ------ 500 



Xli CONTENTS. 

CHAPTER XVII. 

OF THE SPECIAL ANATOMY OF THE SPINAL MARROW AND BRAIN, AS 
DESCRIBED FROM BELOW UPWARDS. 

Of the Medulla Spinalis, ... - 505 

Nucleus of Spinal Marrow, - & 07 

Fissure of Spinal Marrow, - - - 508 

Roots of the Nerves, ... - 509 

Connexion of Nerves with Cord, - - 511 

Medulla Oblongata, - - - - - 514 

Corpus Restiforme, - - - - 516 

Corpus Pyramidale, - - - - -517 

Corpus Olivare, - - - - - 518 

Cerebellum, ------ 519 

Pons Varolii, ----- 524 

Valve of Vieussens, ----- 526 

Cerebrum, .... - 527 

Anterior and Posterior Ganglia of the Brain, - 528 

Corpus Callosum, .... 529 

Tubercula Ouadrigemina, .... 530 

Fornix, - - - - - - 531 

Infundibulum and Pituitary Gland, - 533 

Immediate Origin of the Encephalic Nerves, - 534 

Glossary, ------- 539 



SYSTEM OF ANATOMY. 



PART VII. 

OF THE ABDOMEN. 

The lowermost of the two great cavities of the trunk of the 
body is called Abdomen. The pelvis may be considered as a 
chamber of this cavity, although its structure is very different. 

CHAPTER I. 

A GENERAL VIEW OF THE ABDOMEN AND PELVIS AND THEIR CON- 
TENTS. GENERAL ANATOMY OF THE SEROUS MEMBRANES. OF 
THE PERITONEUM. 

Of the Abdomen. 

This great cavity occupies more than half of the space en- 
closed by the ribs, and all the interior of the trunk of the body 
below the thorax. 

It is formed by the diaphragm, which is supported by the 
lower ribs ; by a portion of the spine ; by the various muscles 
which occur between the lower margin of the thorax and the 
upper margin of the ossa innominata, which contribute, for the 
same purpose, the costce of the ossa ilia, as well as the pelvis. 

The general figure of this cavity partakes of the figure of the 
lower part of the trunk of the body ; with these exceptions, that 

VOL. II. 2 



CONSTRUCTION OF THE ABDOMEN. 

the diaphragm makes it arched or vaulted above, that the spine 
and psoae muscles, &c. are rather prominent on the posterior 
surface, and that the lower part corresponds with the costse of 
the ossa ilia and with the pelvis. 

To acquire a precise idea of this cavity, it is necessary first to 
study the bones concerned in its structure, in their natural situa- 
tion in the skeleton ; and then the muscles, which form so large 
a part of it. 

The arrangement of the tendons of some of these muscles, 
with a view to complete the cavity, is particularly interesting ; 
as that of the external oblique where it forms the crural arch.* 
The ligaments of the pelvis and the levatores ani muscles, as 
they also contribute to the formation of the cavity, and have an 
influence upon its figure, should likewise be attended to. 

In the walls of the cavity, thus constructed, there are many 
foramina, by which the viscera and other contained parts com- 
municate externally ; but few of them pass directly into the 
cavity ; for, like the thorax, there are no vacuities in it, exterior 
to the contained organs. 

Three of these foramina are in the diaphragm. One for the 
transmission of the aorta, another for the vena cava, and a third 
for the oesophagus. Below, there is an aperture at each of the 
crural arches, for the transmission of the great femoral vessels ; 
in each of the ligamentous membranes which close the foramen 
thyroideum, for the obturator vessels and nerve; and at the 
sacro-sciatic notches, for nerves and blood-vessels. 

There are also two apertures at the bottom of the pelvis, for 
the orifice of the rectum and of the urethra. In the tendons of 
the external oblique muscles are two orifices, covered by the 
integuments, for the spermatic cords ; and, in the foetal state, 
one for the umbilical cord. 

The apertures in the tendons, and under their edges, for the 
transmission of the spermatic cords, and the blood-vessels, &c. 
are not to be considered as simple perforations made abruptly ; 



* See the account of this tendon, vol. i. in the description of the " Obliquus 
Descendens Externus." 



CONTENTS OF THE ABDOMEN 



15 



but the edges of these foramina are formed by tendinous mem- 
branes turned inwards, and continued so as to compose a cylin- 
drical tube, which becomes gradually so thin that it cannot be 
readily distinguished from the cellular membrane with which it 
is connected.* The blood-vessels, &c. pass along this tube before 
they go through the apertures. 

It is evident from the construction of this cavity, that it is essen- 
tially different from the thorax. It has no power of spontaneous 
dilation whatever: it yields passively to the distention of the 
stomach and intestines, during deglutition, and when air is ex- 
tricated from the aliment &c. ; but it is particularly calculated 
for compressing its contents by the contraction of the muscles 
which compose it. The diminution of its capacity, which is thus 
effected, not only takes place to a great degree, but occasionally 
with great force. The diaphragm and the abdominal muscles 
may be considered in some measure as antagonists of each other. 
When the diaphragm descends, if the abdominal muscles are 
passive, they are distended by the contents of the abdomen, 
which are forcibly pressed from above : but if the abdominal 
muscles act at the same time, an effort to diminish the cavity in 
every direction takes place, and the contained parts are com- 
pressed with" more or less force according to the exertion made. 
This will be very evident upon examining the situation of the 
diaphragm and of the abdominal muscles. When their force is 
considered, it will also be very obvious that the various outlets 
of the cavity are constructed most advantageously ; otherwise 
hernia or protrusion of its contents would be a daily occurrence. 

The abdomen contains, 1st, The Stomach and the whole In- 
testinal Tube, consisting of the small and the great intestines. 

2d. The Assisti7ig Chylopoietic Viscera, — the Liver, the Pan- 
creas, and the Spleen. 

3d. The Urinary Organs, — the Kidneys, the Ureters, and the 
Bladder. To which should be added the Glandular Renales. 

4th. The Organs of Generation in part : those of the female 



* The student of anatomy, when engaged with this subject, will be gratified by 
the examination of Mr. Astley Cooper's plates relating to hernias. 



jg REGIONS OF THE ABDOMEN. 

sex being almost wholly included in the pelvis; and those of the 
male being situated partly within and partly without it. 

5th. The Peritoneum and its various processes. The Mesen- 
tery, Omentum, &c. 

6th. A portion of the Aorta, and almost the whole of the Inferior 
Cava, and their great ramifications : with such of their branches 
as are appropriated to the Viscera of the Abdomen and Pelvis. 
7th. Those portions of the Par Vagum and Intercostal Nerves 
which are appropriated to the cavity ; and portions of some of 
the nerves destined to the lower extremities. 

8th. The lower part of the Thoracic Duct, or the Great Trunk 
of the Absorbent System, with the large branches that compose 
it, and the glands connected with them: and also those absorbent 
vessels called Lacteals, and their glands. 

As the cavity of the abdomen has no natural divisions, ana- 
tomists have divided it by imaginary lines into various regions, 
with a view to precision in their accounts of the situation of the 
different contained parts. Thus, 

They have, very generally, agreed to apply two transverse 
lines to form three great divisions ; viz. the Upper, Middle and 
Lower: and they have also agreed that each of these divisions 
shall be subdivided into three regions. 

The three regions of the uppermost division are defined with 
some precision. Those on each side, which are called the Right 
and Left Hypochondriac regions, occupy the space immediately 
within the lower ribs and their cartilages; while the middle 
space, included within the margins of these cartilages and a line 
drawn from the lower edge of the thorax on one side to that on 
the other, is denominated the Epigastric region. 
The boundaries of the regions below are less precisely defined. 
Many anatomists have fixed the two transverse lines above 
mentioned,at an arbitrary distanceabove and below the umbilicus: 
some choosing for this purpose two inches, and others a hand's 
breadth. As these distances will occupy different proportions of 
the cavity in persons of different stature, other anatomists, with 
a view to avoid this inconvenience, have proposed to connect 
these lines with certain fixed points of the skeleton. 



REGIONS OF THE ABDOMEN. 17 

It is of importance that the boundaries of these regions should 
be fixed, and therefore the proposition of Sabatier may be 
adopted ; namely, To draw the upper transverse line from the 
most inferior part of the lower margin of the thorax, on one side, 
to the corresponding part on the opposite side ; and the lower 
transverse line from the uppermost part of the spine of one ilium 
to the same part of the other. These lines will mark the three 
great divisions. If, then, two parallel lines are drawn directly 
upwards, one from each of the superior anterior spinous pro- 
cesses of the ilium,* until it touches the lower margin of the 
thorax, they will divide each of the two lower divisions of the 
abdomen into three regions. The centre of the middle division 
is the umbilical, and on each side of it is the right and left lumbar 
region. The middle of the lower division is the hypogastric ; 
and on each side of it the right and left iliac region. 

It is true that the three middle regions of the abdomen will 
be made very small by the vicinity of the transverse lines to 
each other; but the advantages derived from a principle which 
is similar in its application to all subjects, fully compensates for 
this inconvenience. 

There are therefore nine of these regions ; namely, The Epi- 
gastric and the two Hypochondriac: the Umbilical, and the two 
Lumbar : the Hypogastric, and the two Iliac regions.f And it 
should be added, that the space immediately around the end of 
the sternum is sometimes called the Scrobiculus Cordis ; and the 
space immediately within the os pubis, the Regio Pubis. 

These different regions are generally occupied in the follow- 
ing manner : The liver fills nearly the whole of the right hypo- 
chondriac region, and extends through the upper part of the 
epigastric region into the left hypochondriac. The stomach 
occupies the principal part of the epigastric region, and a consi- 
derable portion of the left hypochondriac. The spleen is also situ- 

* Professor Horner makes a more equable division of the cavity of the abdomen, 
by drawing the two vertical lines from the anterior inferior spinous process of the 
ilium, so as to divide each of the three divisions made by the transverse lines, into 
three nearly cquil parts. — p. 

t It is to be observed that the lateral regions of the middle and lower divisions 
of the abdomen are named differently by different writers. 

2 * 



SITUATION OF THE VISCERA IN THE 

ated in the left hypochondriac region. That portion of the in- 
testinal tube, which is composed of small intestines, is generally 
found in the umbilical, the hypogastric, and the iliac regions, 
and when the bladder is empty, in the pelvis. But the duode- 
num, or first of the small intestines, which proceeds immedi- 
ately from the stomach, is situated in the epigastric and umbili- 
cal regions. The great intestine commences in or near the right 
iliac region, and ascends through the right lumbar to the right 
hypochondriac region. It then crosses the abdomen, passing 
through the lower part of the epigastric, or upper part of the 
umbilical to the left lumbar region: from this it continues into 
the left iliac region, and curves in such a manner that it finally 
arrives at the middle of the upper part of the os sacrum, when 
it descends into the pelvis, and, partaking of the curvature of 
the last mentioned bone, continues to the termination of the os 
coccygis. 

In the back part of the epigastric region, and very low down 
in it, is situated the pancreas. The kidneys lie in the most pos- 
terior parts of the lumbar regions, and from each of them is con- 
tinued a tube or duct, called Ureter, that passes into the pelvis to 
convey the urine into the bladder. This viscus, in males, is in 
contact with the last portion of the great intestine called the 
Rectum, and with it occupies almost all the cavity of the pelvis ; 
while in females, the uterus and its appendages are situated be- 
tween this intestine and the bladder. 

In the posterior part of the abdomen, in contact with the spine, 
is the aorta. This great blood-vessel passes from the thorax 
between the crura of the diaphragm, and continues down the 
spine until it approaches towards the pelvis, when it divides into 
two great branches called the Iliac Arteries. Each of these 
great branches divides again, on the side of the pelvis, into two ; 
namely, the External Iliac, which passes under the crural arch 
to the thigh, and the Internal Iliac, or Hypogastric, which de- 
scends into the cavity of the pelvis. 

Soon after the arrival of the aorta in the abdomen it gives off 
two large branches. The first, which is called the Caliac, is dis- 
tributed to the liver, the stomach, and the spleen : the second, 



CAVITY OF THE ABDOMEN. J 9 

called the Superior Mesenteric, is spent upon the intestines. 
Lower down in the abdomen, it also sends off a small branch 
for the intestines, called Inferior Mesenteric. Besides these 
vessels for the chylopoietic viscera, the aorta sends off a large 
branch, called Emulgent, to each kidney. 

The inferior or ascending vena cava is situated on the right 
of the aorta, in front of the spine. It is formed below by the 
union of the iliac veins, and in its progress upwards, it receives 
the emulgent veins, which correspond to the arteries of the kid- 
neys ; but it receives in its course no veins which correspond di- 
rectly with the coeliac and mesenteric arteries. The smaller 
veins that answer to the branches of these arteries, unite and 
form one large vein, which goes to the liver, and is called (from 
the part of that viscus at which it enters,) Vena Portarum. From 
the liver three large veins pass into the vena cava, and deposit 
there the blood of the vena portarum, after it has furnished ma- 
terials for the secretion of bile. The vena cava, in its passage 
upwards, is in close contact with the posterior thick edge of the 
liver: it often passes along a deep groove in this edge, and some- 
times it is completely surrounded by the liver in its course. The 
veins of the liver enter the vena cava at this place, and of course 
they are not to be seen without dissection. Immediately after 
leaving the liver, the vena cava passes through an aperture in 
the tendinous centre of the diaphragm to unite itself to the right 
auricle of the heart. 



20 



EXPLANATION OF PLATE VIII. 



Fig. 1. Shows the Contents of the Thorax and Abdomen in situ. 

1. Top of the Trachea, or windpipe. 2, 2, The internal jugular veins. 
3,3, The subclavian veins. 4, The vena cava descendens. 5, The right 
auricle of the heart. 6, The right ventricle. 7, Part of the left ventricle. 
8, The aorta descendens. 9. The pulmonary artery. 10, The right lung, 
part of which is cut off to show the great blood-vessels. 11, The left lung 
entire. 12, 12, The anterior edge of the diaphragm. 13, 13, The two great 
lobes of the liver. 14, The ligamentum rotundum. 15, The gall-bladder. 
16, The stomach. 17, 17, The jejunum and ilium. 18, The spleen. 

Fig. 2. Shows the Organs subservient to the Chylopoietic Viscera, — with 
those of Urine and Generation. 

1, 1. The under side of the two great lobes of the liver, a, Lobulus spi- 
gelii. 2, The ligamentum rotundum. 3. The gall-bladder. 4, The pan- 
creas. 5, The spleen. 6, 6, The kidneys. 7, The aorta descendens. 8, 
Vena cava ascendens. 9, 9, The renal veins covering the arteries. 10, A 
probe under the spermatic vessels and a bit of the inferior mesenteric artery, 
and over the ureters. 11, 11, The ureters. 12, 12, The iliac arteries and 
veins. 13, The intestinum rectum. 14, The urinary bladder. 

Fig. 3. Shows the Chylopoietic Viscera, and Organs subservient to them, 
taken out of the body entire. 

A A, The under side of the two great lobes of the liver. B. Ligamentum 
rotundum. C, The gall-blader. D, Ductus cysticus. E, Ductus hepa- 
ticus. F, Ductus communis choledochus. G, Vena portarum. H, Arteria 
hepatica. I, The stomach. K K, Venae and arteria? gastro-epiploicae, dex- 
trae and sinistra?. L L, Vena? and arteria? coronariae ventriculi. M, The 
spleen. N N, Mesocolon, with its vessels. OOO, Intestinum colon. P, 
One of the ligaments of the colon, which is a bundle of longitudinal mus- 
cular fibres. QQQQ, Jejunum and ilium. R R, Sigmoid flexure of the 
colon with the ligament continued, and over, S, The intestinum rectum. 
T T, Levatores ani. U, Sphincter ani. V, The place to which the pro- 
state gland is connected. W, The anus. 

Fig. 4. Shows the Heart of a Foetus at the full time, with the Right Au- 
ricle cut open, to show the Foramen Ovale, or passage between both 
Auricles. 

a, The right ventricle, b, The left ventricle, cc, The outer side of 
the right auricle stretched out. d d, The posterior side, which forms the 




w 



^ 



V ''• 




— 




EXPLANATION OF PLATE VIII. 



21 



anterior side of the septum, e, The foramen ovale, with the membrane or 
valve which covers the left side, f, Vena cava inferior passing through, g, 
A portion of the diaphragm. 

Fig. 5. Shows the Heart and Large Vessels of a Foetus at the full time. 

a, The left Ventricle, b, The right ventricle, c, A part of the right 
auricle, d, Left auricle, e e, The right branch of the pulmonary artery, 
f, Arteria pulmonalis. g g, The left branch of the pulmonary artery, with 
a number of its largest branches dissected from the lungs, h, The canalis 
arteriosus, i, The arch of the aorta, k k, The aorta descendens. 1, The 
left subclavian artery, m, The left carotid artery, n, The right carotid 
artery, o, The right subclavian artery, p, The origin of the right carotid 
and right subclavian arteries in one common trunk, q, the vena cava su- 
perior or descendens. r, The right common subclavian vein, s, The left 
ocmmon subclavian vein. 

N. B. All the parts described in this figure are to be found in the adult, 
except the canalis arteriosus. 



2 GENERAL ANATOMY 

i 

General Anatomy of Serous Tissues. 
—The serous tissue, is found in every part of the body where 
there is an habitual movement of parts upon each other. Its 
object appears to be to diminish friction and to facilitate motion, 
by the glassy smoothness of the free surfaces which it presents, 
and by its pouring out continually a lubrifying liquid between the 
surfaces where motion occurs. The serous system consists of a 
great number of membranes, forming closed sacs,* which are ad- 
herent by their external surface to the organs which they line ;— 
their internal surface is free and smooth, and secretes a fluid, with 
which they are constantly, in a healthy state, moistened, analogous 
to the serum of the blood. The adhesion of the outer surface of 
the serous tissues to the subjacent parts, is so intimate in most 
places, that it has only been within latter times, by the labours of 
Bonn, Monro, and Bichat, that their proper character has been 
determined. They consist of the peritoneum, the pleura, the peri- 
cardial lining membrane, the arachnoid of the brain and spinal 
marrow, the tunica vaginalis testis, and the synovial capsulesf of 
the joints and tendons. The serous membranes are all ex- 
tremely thin, delicate and of a transparent whiteness; they are 
attached to the parts they cover by the intermedium of cellular 
tissue, which in some parts is long and loose, and in others so 
short and dense as to be scarcely discernible and to which they 
seem to form a simple serous facing. Hence Bordeu, and Ru- 
dolphi were disposed to consider it as a modification of cellular 
tissue, formed by the flattening of the cells of the latter. 
— Though this is true probably in regard to their ultimate struc- 
ture, yet since they exist, as Bichat has shown us, as distinct mem- 
branes in the early periods of foetal life, and as their diseases 
exhibit peculiar phenomena, they deserve to rank among the 
elementary tissues of the body. Some of the serous membranes 
consist merely of a simple bag of greater or less size — some line 

* The peritoneum of the female, which has the fallopian tube opening into its 
cavity, is the only instance of a serous membrane which is not a closed sac. — p. 

| The synovial membranes were considered by Bichat as forming a distinct tis- 
sue, which he named synovial. — p. 



OF THE SEROUS MEMBRANES. 



23 

cavities which are very irregular in surface and shape — and 
others, like the pleura and peritoneum, are reflected over the 
inner face of the viscera, like the internal fold of the double 
night-cap over the head, and presenting a very complicated ar- 
rangement, so that the viscera which the membrane lines are 
necessarily left upon its outer side- All the vessels which enter 
these viscera, pass between the two layers that form the roots of 
the folds by which they are embraced. (See Fig. 43, p. 26.) 
— In the healthy state the serous membranes are perfectly white 
and insensible; and when in a state of inflammation, the appa- 
rent redness of the membrane is frequently owing to the injection 
of the sub-serous cellular tissue. Nevertheless they contain a 
vast number of serous capillary vessels, which Ruysch suc- 
ceeded in injecting in such abundance, as to be led to think they 
were composed chiefly of these vessels. Mascagni was equally 
successful in filling their lymphatics, and considered these vessels 
the principal elements in the composition of serous tissues. 
Both, therefore, exist in great numbers, and woven together with 
some intermediate connecting fibres like those of the cellular 
tissue, constitute these membranes. This, too, is the ultimate 
composition of cellular tissue as proved by the recent researches 
of Miiller and Treviranus. (See vol. i. p. 371.) The serous mem- 
branes are said to yield gelatine by boiling, and in this respect 
also they agree with the cellular membrane. The serous capil- 
laries pour out a lubricating serous fluid, (called halitus from 
its vapoury condition during life, and which condenses as the 
body cools after death,) by a process called exhalation, which we 
do not fully understand, and which the absorbents gradually re- 
move during health, so as to prevent its accumulation. But when 
the usual healthy balance of action between them is disturbed, 
by too copious exhalation, or languid absorption, dropsy may 
take place in any one of what are called the serous cavities of 
the body. There is not in fact, though the term is in general 
use, any cavity or unoccupied space in the interior of any of 
these membranes. In the healthy state, organ is in contact with 
organ, and the reflected membranes with which they are lined, 
slide over those which line the parietes of the so called cavities. 



24 THE PERITONEUM. 

And when the area of a joint is suddenly enlarged, as those of the 
fingers may be by pulling at the phalanges, the fluid within be- 
comes rarified to fill the vacuum, and is the cause of the snapping 
noise heard when the bones return in contact. The same phe- 
nomenon is sometimes observed in mastication, produced by the 
relaxation of the ligaments of the temporo-maxillary articulation. 
— Though no nerves have been traced satisfactorily to the 
serous membranes, and they appear to possess little or no sen- 
sation in a physiological state, they become exquisitely sensitive 
when suddenly inflamed, as in pleuritis. — 

Of the Peritoneum. 
The abdomen, thus constructed and occupied, is lined by a 
thin firm membrane called Peritoneum, which is extremely 
smooth on its internal surface, and is immediately connected 
with the cellular substance exterior to it. This membrane ad- 
heres closely to the anterior, lateral and superior portions of the 
surface of the abdomen ; and is extended from the posterior sur- 
face so as to cover, more or less completely, the viscera of the 
cavity. 

Fig. 42.* 




Those viscera which are in close contact with the poste- 
nor surface of the abdomen, as some portions of the large in- 

Ion. e, Small intestine. /, descending colon T r ■ ' AsCend,n £ co " 



THE PERITONEUM. 



25 



testine, are covered only on their anterior surfaces, and are fixed 
in their precise situation by the peritoneum ; which extends from 
them to the contiguous surface of the cavity, and adheres where 
it is in contact, so as to produce this effect. 

Other viscera, which are not in close contact, but movable 
to a distance from the posterior surface of the abdomen, are 
covered by this membrane, which is extended to them from the 
surface; and this extended portion forms an important part of 
the connexion between the viscus and the cavity in which it lies. 
This connecting part is called Mesentery, when it thus passes to 
the small intestines ; Mesocolon, when it goes to the colon, one 
of the larger intestines ; and Ligament, when it passes to some 
of the other viscera. 

The peritoneum is a complete but empty sac, which is fixed 
in the abdomen anterior to the viscera. The anterior portion of 
this sac forms the lining to the anterior and lateral parts of the 
surface of the abdomen : the posterior portion covers the vis- 
cera, and forms the mesentery, mesocolon, and ligaments above 
described. 

It necessarily follows that the mesentery and the other similar 
processes are mere plaits or folds of the sac, which invests the 
viscera; and that they must consist of two lamina; and as the 
blood-vessels, nerves, and absorbents, are all posterior to the 
peritoneum, they naturally pass between these lamina of the 
mesentery. 

Some of the viscera are much more completely invested with 
the peritoneum than others. The stomach, liver, and spleen are 
almost completely surrounded by it ; and it is said to form a 
coat for each of these viscera. That portion of the smaller in- 
testinal tube, which is called jejunum and ileum, and the trans- 
verse portion of the large intestine, called the arch of the colon, 
are invested by it in the same way. But a considerable portion 
of the duodenum and the pancreas is behind it. The lateral por- 
tions of the colon are in close contact with the posterior surface 
of the abdomen, and the peritoneum only covers that portion of 
their surfaces which looks anteriorly towards the cavity of the 
abdomen, and is not in contact with its posterior surface. 

VOL. II. 3 



__ THE PERITONEUM. 

2b 

The urinary organs are not much connected with the perito- 
neum. The kidneys appear exterior to it, and behind it: the 
bladder of urine is below it, and has but a partial covering irom 
it, on its upper portion. 

The peritoneum, which covers the stomach, is extended irom 
the great curvature of that organ so as to form a large mem- 
brane, which descends like an apron before the intestines This 
process of peritoneum is composed of two lamina, so thin and 
delicate as to resemble cellular membrane, which, after extend- 
ing downwards to the lower part of the abdomen, are turned 
backwards and upwards, 



and proceed in that direction 
until they arrive at the colon, 
which theyenclose, and then 
continue to the back of the 
abdomen, forming the meso- 
colon. The part of this pro- 
cess which is between the 
stomach and the colon, is 
called Epiploon or Omentum. 
This extension of a mem- 
brane, from the surface of a 
cavity which it lines, to the 
external surface of a viscus 
in that cavity, is called by 
some anatomists, " reflec- 
tion;" and the technical term 
reflected membrane is there- 
fore applied to a membrane 
distributed like the perito- 
neum. 

It must be evident that 
this distribution of the peri- 



Fig. 43J 




* Fig. 43 is a diagram, illustrating the reflections of the peritoneum, a, 
Umbilicus, b, 6, Diaphragm, c, Liver, d, Stomach, e, Transverse colon. /, Duo- 
denum, g, Pancreas, h, Small intestine, t, Vertebral column, k, Promontory 
of the sacrum. I, Rectum, m, Uterus, n, Bladder, o, Symphysis pubis, p, 



THE PERITONEUM. 



27 



toneum is very complex, and that it is not easy to form an accu- 
rate conception of it from description, but it can be readily un- 
derstood by demonstration ; therefore no farther account of its 
arrangement will now be attempted, but each of its processes 
will be considered with the organs to which they are particu- 
larly subservient. 

That portion of the peritoneum which lines the abdomen, 
and covers the viscera, is thin and delicate, but very firm. It 
yields to distention, as in pregnancy, ascites, &c, and again 
recovers its dimensions. It was formerly thought to be com- 
posed of two lamina, but this cannot be proved. The internal 
surface of this membrane is very smooth, and highly polished ; 
and from it exudes a liquor which is well calculated for lubrica- 
tion, and barely sufficient to keep the surface moist during health ; 
but sometimes it is very abundant, and occasions the aforesaid dis- 
ease — ascites. This fluid appears to exude from the surface of 
the peritoneum when it is compressed in a living animal, or one 
recently dead. It is probably effused from the extremities of 
arteries, for an effusion takes place when water is injected into 
these vessels. 

The peritoneum abounds with absorbent vessels, and there- 
fore possesses the power of absorption to a great degree. This 
power may be inferred, not only from the spontaneous removal 
of the fluid of ascites, but if milk and water be introduced into 
the abdomen of a living animal, through a puncture, it will also 
disappear. 

The blood-vessels of the peritoneum are derived from those 
which supply the neighbouring parts. Nerves have not yet been 
traced into it, and it has little or no sensibility. 

This membrane supports the viscera of the abdomen in their 
proper situations ; and also forms a surface for them, and for the 
cavities which contain them, so smooth and lubricated, that no 
injury can arise from their friction. 

The cellular substance, by which the peritoneum is connected 

Coronary ligament of the liver, q, Omentum minus or hepatico-gastricum. r, 
Omentum majus, or gastro-colicum. s, Transverse mesocolon. /, Sac of the 
omentum majus. u, Mesentery. — p. 



28 THE PERITONEUM. 

to the contiguous parts, is very different in different places. It 
is very short indeed between this membrane and the stomach 
and intestines, and also between it and the tendinous centre of the 
diaphragm. Between the peritoneum and the muscles generally, 
it is much longer. When it covers the kidneys and the psoas 
muscle, it is very lax and yielding. About the kidneys a large 
quantity of adeps very commonly collects in it. On the psoas 
muscle it yields with but little resistance to the passage of pus, 
or any other effused fluid, as in the case of the psoas abscess. 



GENERAL SrRUCTURE OF THE ALIMENTARY CANAL. 



29 



CHAPTER II. 

OF THE GENERAL STRUCTURE OF THE ALIMENTARY CANAL, OF 
THE (ESOPHAGUS, THE STOMACH, AND THE INTESTINES. 

General Structure of the Alimentary Canal. 

— This canal, formed of the oesophagus, stomach, and intes- 
tines, extends inclusively from the pharynx to the anus. It is 
composed throughout, (with the exception of the oesophagus, the 
transverse part of the duodenum, and the termination of the rec- 
tum, which want the serous coat,) of four membranes or tunics; 
an internal mucous coat, one exterior to this, fibro-cellular or ner- 
vous, a third more external still, which is muscular ; and of a 
fourth investing serous coat, which is derived from the perito- 
neum lining the cavity of the abdomen. There enter also into 
its composition, mucous glands, nerves, blood-vessels, and absorb- 
ents. The arrangement of the serous tunic varies in different 
portions of the canal; but its general arrangement is such, that it 
embraces the canal, and serves as a ligament to connect it to 
the back and lateral parts of the abdominal parietes, so as effec- 
tually to prevent any entanglement or knotting in the folds of 
the canal, and at the same time allow it great latitude of mo- 
tion. It is united to the outer face of the muscular coat, by cel- 
lular tissue. The muscular tunic is of a pale colour, soft, and 
easily lacerated. 

— The muscular tunic consists throughout of two orders of fibres, 
a circular which is internal, and a longitudinal which is external. 
The former are not entirely circular, but consist of segments, 
which, by their reunion, constitute perfect circles. The latter do 
not run the whole length of the tube, but are interrupted after 
short courses. Both may be considered as having their origin and 
insertion in the fibro-cellular tunic, which separate them from the 

3 • 



30 



THE (ESOPHAGUS. 



mucous membrane. The fibro-cellular (cellular or *^™£> 
forms a perfect cylinder, and is composed of fibres of condensed 
cellular tissue intercrossed in different directions. It is the 
strongest of all the tunics, and gives to the canal its greatest 
power of resisting internal distention. The nerves ramify abun- 
dantly in this tunic before they reach the mucous, and hence the 
organic suffering and often sudden death, resulting from sudden 
tympanitic distention of the alimentary canal. The mucous mem- 
brane of the canal is every 
where continuous. It is of a ^g"- 4 

reddish colour, soft and fungous 
in its consistence, and varies in 
its thickness, and in the number 
of the villi, follicles, and folds, 
which it forms in different por- 
tions of the canal. — 

Of the (Esophagus. 

The (Esophagus is a mus- 
cular tube which passes from 
the pharynx to the stomach, 
and is so intimately connected 
with the stomach, that it will 
be advantageous to the student 
to attend to its structure imme- 
diately before he engages in the examination of that important 
organ. 

* Fig. 44. The pharynx slit open behind, in order to show the relative position 
of the opening of the posterior nares, the velum pendulum palati, the floor of the 
mouth, and the opening of the larynx, a, Base of the cranium, b, Mastoid pro- 
cess of the temporal bone, c, Vertical partition between the nasal fossce, of which 
is seen the termination behind, d, Velum pendulum palati, a fleshy appendage to 
the osseous palate; at its middle part, projecting downwards and backwards is seen 
the uvula, and on each side of the uvula, are seen the buccal cavities, e, Base of the 
tongue. /, Extremity of the os hyoides ; on the opposite side, this bone is entirely 
concealed, by the portion of the posterior wall of the pharynx, which is folded 
outwards, g, Glottis, or opening of the larynx; the epiglottis is seen above and in 
front of this opening, and is in this figure applied against the base of the tongue. 
h, Part of the trachea, i, Commencement of the oesophagus, k, Levator pharyn- 
geus muscle. — p. 




THE OESOPHAGUS. gj 

— The commencement of the cavity of the pharynx, from the 
base of the cranium, and its position behind the posterior open- 
ing of the cavities of the nose, mouth, and glottis, are well seen 
in Fig. 44, page 30. Its termination below, and the commence- 
ment of the oesophagus are seen at i. — 

The pharynx has been lately described* as composed of a 
varied stratum of muscular fibres, lined by a membrane which 
is continued from the internal surface of the nose and mouth. 
From the pharynx the oesophagus passes downwards between 
the trachea, and the vertebra;. After the bifurcation of the tra- 
chea, it proceeds in contact with the spine, between the lamina 
of the mediastinum, to the diaphragm, which it passes through, 
and then terminates in the stomach. 

The oesophagus is a flexible tube, which, when distended, is 
nearly cylindrical. It consists of a muscular coat externally, 
and an internal tunic evidently continued from that of the pha- 
rynx. These coats are connected by a collular substance called 
the Nervous Coal,] which is remarkably loose, and allows them 
to move considerably upon each other. The muscular coat, 
which is very distinguishable from that of the pharynx, consists 
of two substantial strata of fibres; the exterior of which is 
nearly longitudinal in its direction, and the interior circular 
or transverse. 

— The longitudinal fibres appear to arise in part from the 
posterior face of the cricoid cartilage, between the posterior 
crico-arytenoid muscles, and part from the lower end of the 
pharynx; they are disposed regularly around the oesophagus, 
and below are manifestly continuous with the longitudinal mus- 
cular fibres of the stomach. The first ring of the circular fibres, 
also seems to arise from the cricoid cartilage, and has been de- 
scribed as the crico-oesophageal muscle. There is no sphincter, 

* Sec vol. i. p. 446. 

t The nervous coat, is nothing but a structure of submucous cellular tissue, 
which connects the mucous membrane, as the subcutaneous does the skin, to the 
parts subjacent, and through which the nerves and blood-vessels ramify, before 
they spread minutely in the mucous membrane. — p. 



32 THE CESOrHAGUS. 

at the junction of the oesophagus with the stomach as has been 
asserted by some anatomists. 

—The muscular coat of the oesophagus is next in thickness to 
that of the pharynx, and thicker than that of any other portion 
of the alimentary canal. — 

The internal coat of the oesophagus, resembling that of the 
fauces, is soft and spongy. It is covered with a very delicate 
cuticle, which Haller supposed to be too tender to confine the 
matter of variolous pustules, as he had never found these extend- 
ing into the oesophagus. It is very vascular, and abounds with 
the orifices of mucous follicles, from which is constantly poured 
out the mucus that is spread over this surface. When the oeso- 
phagus is not distended, many longitudinal plaits are found in 
this membrane by the contraction of the circular or transverse 
fibres exterior to it. These plaits are calculated to admit readily 
of the distention which is requisite in deglutition. This tunic is 
continued from the lining membrane of the pharynx above, and 
terminates below in the villous coat of the stomach ; from which, 
however, it is very different. 

— The cuticle terminates by an irregularly fringed or festoon- 
ed border at the cardiac orifice, where the oesophagus termi- 
nates, and is insensibly lost upon the mucous membrane of the 
stomach. The mucous membrane of the oesophagus, like that 
of the rectum (and unlike that of any other portion of the ali- 
mentary canal,) is united by a very loose cellular tissue to the 
inner face of the circular stratum of fibres, so that it may be 
withdrawn as a cylindrical tube from the muscular sheath in 
which it is contained. 

— Experimenters upon living animals have asserted that they 
have seen the muscular coat, force by its contraction the mu- 
cous membrane downwards, so as to cause it to form a circular 
tumour, much like that of the mucous membrane of the rectum, 
in prolapsus ani. — 

The blood-vessels of the oesophagus come from the aorta and 
those which are in the vicinity. The nerves are derived from 
the eighth pair. The lymphatic vessels are very abundant. 

In the neck the oesophagus inclines rather to the left of the 



FORM OF THE STOMACH. gg 

middle line. As it proceeds down the back between the lamina 
of the mediastinum, it preserves the same course to the fourth 
dorsal vertebra, when it assumes the middle portion and pro- 
ceeds downwards, with the aorta to its left, and the pericardium 
before it. About the ninth dorsal vertebra it inclines again 
rather to the left, and somewhat forward, to arrive at the aper- 
ture in the diaphragm through which it passes. 

Throughout this course it is connected by cellular membrane 
to the contiguous parts ; and this investiture of cellular mem- 
brane has been called its External Coat. 

While the oesophagus is in the posterior mediastinum it is in 
contact with several small absorbent glands, especially when it 
first assumes a situation to the right of the aorta. These glands 
were formerly believed to be particularly connected with this 
tube, but they are now considered as belonging to the absorbent 
system. They are sometimes greatly enlarged. 

Of the Stomach. 

This most important organ, which occasionally exerts a 
powerful influence upon every part of the body, appears very 
simple in its structure. 

It is a large sac, which is so thin when much inflated, that at 
first view it seems membranous, but upon examination is found 
to be composed of several lamina or coats, each of a different 
structure. It is of considerable length, but incurvated. It is 
much larger at one extremity than the other, and changes so 
gradually in this respect, that it would appear conical, if it were 
straight. It is not, however, strictly conical, unless it is greatly 
distended ; for when moderately distended, a transverse section 
is rather oval than circular. It is, therefore, considered as 
having two broad sides or surfaces, and two edges, which are 
the curvatures. It has been compared by the anatomists of 
different nations to the wind sac of the musical instrument called 
the bagpipe.* The orifice in which the oesophagus terminates 

* The student ought not to attempt to acquire an idea of the form of the sto- 
mach without demonstration, for a view of one moment will be more serviceable 
than a long description. 



34 POSITION OP THE STOMACH. 

is at a small distance from its largest extremity, and is called 
Cardia. The orifice which communicates with the intestines is 
at the termination of its small incurvated extremity, and is called 
the Pylorus. 

The two ends of the stomach being thus very different in size, 
are denominated the great and small extremities. The two 
curved portions of the surface are also called the great and small 
curvatures. The two flat portions of the surface or the broad- 
sides, are called the anterior and posterior surfaces. 

The situation of the stomach in the abdomen is nearly trans- 
verse: it lies principally in the left hypochondriac and epigastric 
regions, immediately below the liver. The great extremity of 
the stomach is in the left hypochondriac region, and the lesser 
extremity in the epigastric region, under the left lobe of the 
liver. The upper orifice, or Cardia, is nearly opposite to the 
body of the last dorsal vertebra ; and owing to the curved form 
of the stomach, the other orifice, or Pylorus, is situated at a small 
distance to the right of that bone, and rather lower and more 
forward than the cardia: both orifices being in the epigastric 
region. The position of the stomach is oblique in two respects ; 
it inclines in a small degree from above downwards, from the 
left to the right ; and it also inclines downwards and forwards, 
from behind. Its two orifices are situated obliquely with respect 
to each other; for, if the stomach, when placed with its small 
curvature upwards, were divided into two equal parts by a ver- 
tical plane passing lengthways through it, they would be found 
on different sides of the plane. 

As the oesophagus terminates in the stomach immediately after 
it has passed through an aperture of the diaphragm, it is evident 
that the stomach must be somewhat fixed at that place ; but it is 
more movable at its other orifice; for the extremity of the 
duodenum, into which it is continued, is movable. 

The stomach is connected to the concave surface of the liver 
by the reflection or continuation of the peritoneum which forms 
the lesser omentum. This membrane, after extending over each 
surface of the stomach, continues from its great curve in the 
form of the large omentum, and connects it to different parts, 



SEROUS OR EXTERNAL COAT OF THE STOMACH. 35 

especially to the colon. There are likewise folds of the peri- 
toneum, as it passes from the diaphragm and from the spleen to 
the stomach, which appear like ligaments. 

Notwithstanding these various connexions, the stomach under- 
goes considerable changes in its position. When it is nearly 
empty, and the intestines are in the same situation, its broad 
surfaces are presented forwards and backwards; but when it is 
distended, these surfaces are presented obliquely upwards and 
downwards, and the great curvature forwards. When its an- 
terior surface is presented upwards, its orifices are considerably 
influenced in their direction, and the oesophagus forms an angle 
with the plane of the stomach. 

The stomach is composed of four dissimilar lamina, which 
may be demonstrated by a simple process of dissection. 

There is a first coat or external covering continued from the 
peritoneum : within this, and connected to it by delicate cellular 
substance, is a coat or stratum of muscular fibres : contiguous 
to these fibres, internally, is a layer of dense cellular substance, 
called a nervous coat; and last is the internal coat of the stomach, 
called villous or fungous, from the structure of its surface. 

The external or first coat of the stomach, as has been already 
stated, is continued from the concave surface of the liver to the 
lesser curve of the stomach in two delicate lamina, which sepa- 
rate when they approach the stomach, and pass down, one on 
each side of it, adhering firmly to it in their course: at the op- 
posite curve of the stomach they again unite to form the great 
omentum. The stomach is therefore closely invested by the 
peritoneum on every part of its surface except two strips, one at 
the lesser and the other at the greater curvature. These strips 
or uncovered places are formed by the separation of the lamina 
above mentioned, which includes a triangular space bounded by 
the stomach and these two lamina. In these triangular spaces, 
at each curvature of the stomach, are situated the blood-vessels 
which run along the stomach in those directions, and also the 
glands which belong to the absorbent vessels of this viscus. The 
peculiar arrangement of the lamina at this place is particularly 
calculated to permit the dilatation of the stomach. When it is 



ng MUSCULAR COAT OF THE STOMACH. 

dilated, the lamina are in close contact with its surface, and the 
blood-vessels being in the angle formed by the adhesion of the 
two lamina to each other, are so likewise : when it contracts, 
the blood-vessels appear to recede from it, and the lamina are 
then applied to each other. 

Where the peritoneum thus forms a coat to the stomach, it is 
stronger and thicker than it is between the liver and stomach. 
In a recent subject it is very smooth and moist, but so thin that 
the muscular fibres, blood-vessels, &c. appear through it. If it 
is carefully dissected from the muscular coat, it appears some- 
what flocculent on that surface which adhered to the muscular 
fibres. It seems to be most abundantly furnished with serous 
vessels ; but it has been asserted by Mascagni and Soemmering, 
that a large proportion of its texture consists of absorbent vessels. 
The cellular substance which connects this to the muscular coat, 
appears no way different from ordinary cellular membrane. 

The Muscular Coat of the stomach has been described very 
differently by respectable anatomists ; some considering it as 
forming three strata or fibres, and others but two. If the stomach 
and a portion of the oesophagus attached to it be moderately 
distended with air, and the external coat carefully dissected 
away, many longitudinal fibres will appear on every part of it, 
that evidently proceed from the oesophagus: these fibres are 
particularly numerous and strong on the lesser curvature of the 
stomach. — Beside the longitudinal fibres, there are many that 
have a circular direction, and these are particularly numerous 
towards the small extremity; but it has been doubted whether 
there are any fibres in the muscular coat of the stomach that go 
directly round it. The whole surface of the stomach, when the 
peritoneal coat is removed, appears at first view to be uniformly 
covered by muscular fibres; but upon close examination, there 
are interstices perceived, which are occupied with firm cellular 
membrane. 

—The longitudinal or superficial fibres of the stomach, many 
of which can be traced from the esophagus over the cardiac 
orifice of the stomach, are grouped together so as to form a 
thicker and stronger layer along the lesser curvature of the 



CELLULAR OR NERVOUS COAT OF THE STOMACH. 37 

stomach ; many of these, if traced with care, will be found con- 
tinuous with the longitudinal fibres of the duodenum, and many 
which are terminated by insertion in the cellular coat of the 
stomach near the pylorus. The circular fibres constitute the 
sphincter muscle of the pylorus, by being thickened into a mus- 
cular band at the line of separation between the stomach and 
duodenum. There is another order of fibres called the oblique, 
which are few in number, spread over the left extremity or 
greater tuberosity. But it seems an unnecessary degree of re- 
finement, to consider these other than the circular altered in 
their direction, by the expansion which that part of the stomach 
undergoes shortly after birth. They cannot well be studied 
except in cases where the muscular coat of the stomach is in a 
state of hypertrophy. 

— The use of these oblique fibres, appears to be, to compi*ess the 
great tuberosity of the stomach, and force the matters which it 
contains into the body of the stomach and towards the pylorus. 
The muscular fibres of the stomach are pale, and present in 
regard to colour, the appearance of ligamentous fibres, for which 
they were mistaken by Helvetius and Winslow. This appearance 
is common likewise, to the muscular fibres of the intestinal canal, 
and of the bladder. 

— In the young infant, the shape of the stomach is more tubular, 
and like that of an intestine; its left or splenic pouch not having 
yet been formed. Hence vomiting occurs so much more readily 
in the child than in the adult, the axis of the stomach in the 
latter, corresponding at its two extremities more nearly with that 
of the cardiac and pyloric orifices. 

— The cardiac orifice of the stomach is not provided with any 
sphincter, as it was thought to be by the ancients. — 

In contact with the internal surface of the muscular coat is 
the cellular stratum, which has been called the Nervous Coat of 
the stomach. It is dense and firm, of a whitish colour, resembling 
condensed cellular membrane. It was considered as different 
from ordinary cellular membrane ; but if air be insinuated into 
its texture, by blowing between the muscular and villous coats, 
while it connects them to each other, it exhibits the proper ap- 

vol. 11. 4 



gg INTERNAL OR MUCOUS COAT. 

pearance of cellular substance. It, however, adds greatly to the 
general strength of the stomach, and the vessels which terminate 
in the villous coat ramify in it. 

—The cellular coat is the most resisting of all the tunics of 
the stomach, and may be considered as the basis or frame-work 
of its structure. It is more closely united to the muscular coat 
on its outer face, than to the mucous on its inner. Its attachment 
to the latter, will be seen on close inspection, to be by means of 
a substratum of delicate cellular tissue. — 

The internal coat of the stomach in the dead subject is com- 
monly of a whitish colour, with a tinge of red. It is named 
villous, from its supposed resemblance to the surface of velvet. 
It has also been called fungous, because the processes analogous 
to the villi are extremely short, and its surface has a granulated 
appearance; differing in these respects from the internal surface 
of the intestines. It is continued from the lining membrane of 
the oesophagus, but is very different in its structure. Many very 
small vessels seem to enter into its texture, which are derived 
from branches that ramify in the nervous coat. It is supposed 
by several anatomists of the highest authority, to have a cuticle 
or epithelium ; and it is said that such a membrane has been 
separated by disease. It ought, however, to be remembered, 
that the structure of the villous coat of the stomach and intestines, 
is essentially different from the structure of the cuticle. 

The internal coat of the stomach is generally found covered, 
or spread over with mucus, which can be readily scraped off. 
This mucus is certainly effused upon it by secreting organs, and 
it has been supposed that there were small glandular bodies ex- 
terior to the villous coat, which furnished this secretion ; but the 
existence of such bodies is very doubtful, as many skilful anato- 
mists have not met with any appearance that could be taken 
for glands, except in a very few instances, which would not be 
the case if those appearances had been natural. Pores, perhaps 
the orifices of mucous follicles, and also of exhalent vessels, are 
very numerous, but no proper glandular masses are attached to 
them. Glands, as has been already said, are found in the trian- 
gular spaces between the lamina of the peritoneum at the great 



GASTRIC LldUOR. gg 

and small curvatures of the stomach, but these evidently belong 
to the absorbent system.* Besides the mucus above mentioned, 
a large quantity of a different liquor, the proper Gastric Juice, 
or fluid of the stomach, is effused from its surface. It has been 
supposed that this fluid is furnished by the small glandular 
bodies believed to exist between the coats of this organ; but, 
admitting the existence of these glands, they are not sufficiently 
numerous to produce so much of it as is found, and it is there- 
fore probable that this fluid is discharged from the orifices of ex- 
halent vessels in the internal surface. 

Much information respecting the gastric liquor has been ob- 
tained within a few years past by the researches of physiologists, 
and they are generally agreed that it is the principal agent in 
the effects produced by the stomach upon alimentary sub- 
stances.! 

As the muscular coat of the stomach frequently varies its di- 
mensions, the villous and nervous coats, which have no such 
power of contraction, cannot exactly fit it. They therefore ge- 

* The mucous coat of the stomach is, in its healthy state, thinner, softer, and 
more vascular in the cardiac half of the stomach, than in the pyloric. The villi 
are better developed in the pyloric region. The place of glands in the stomach is 
supplied mainly by muciparous follicles, which are microscopical in regard to size. 
In pathological conditions of the membrane, these follicles sometimes appear 
round, or ovular, globular or flattened, and are believed to be analogous in structure 
and function, to the blennogenous apparatus of Breschet. The mucus in the lat- 
ter case, assisting to form the cuticle, a covering which does not extend farther 
down the alimentary canal than the cardiac orifice of the stomach, at which place 
it terminates, as Chaussier first observed, in a crescentic margin. — p. 

t On this subject, the student may consult with advantage — 

M. Reamur. In the Memoires of the Academy of Sciences for 1752. 

John Hunter. London Philosophical Transactions for 1772; and also his ob- 
servations on the Animal Economy, 1786. 

Dr. Edward Stevens. Inaugural Thesis de Alimentorum Concoctione, Edin- 
burgh, 1777. 

The Abbe Spalanzani. Dissertations relative to Natural History, &c. The 
first volume of the English translation contains the author's dissertations on di- 
gestion, and also the first paper of Mr. Hunter, and the Thesis of Dr. Stevens, as 
well as an account of the experiments of Mr. Gosse of Geneva. 

In addition to these, there are several interesting essays in the French, German, 
and Italian languages, a compilation of which is to be found in Johnson's "His- 
tory of the Progress and present State of Animal Chemistry." See vol. i. p. 158. 



40 PYLORUS. 

nerally appear larger, and of course are thrown into folds or 
ruga?. These folds are commonly in a longitudinal direction; 
but at the orifices of the stomach they are arranged in a radia- 
ted manner, and sometimes they are observed in a transverse 
direction. They depend upon the contraction of the muscular 
fibres, and disappear entirely when the stomach is laid open and 
spread out. 

At the lower orifice is a circular fold, which is permanent, 
and constitutes the valve denominated Pylorus. It appears like 
a circular septum with a large foramen in its centre, or like a 
flat ring. The villous and nervous coats of the stomach contri- 
bute to this, merely by forming the circular fold or ruga ; and 
within this fold is a ring of muscular fibres, evidently connected 
with the circular fibres of the muscular coat of the stomach, 
the diameter of which at this place is not larger than that of an 
intestine : the fibres of this ring seem a part of the muscular 
coat projecting into the cavity of the stomach and duodenum. 
If a portion of the lesser extremity of the stomach and the ad- 
joining part of the duodenum be detached, and laid open by a 
longitudinal incision, and then spread out upon a board, the in- 
ternal coat can be very easily dissected from the muscular, and 
the pylorus will then appear like a ridge or narrow bundle of 
muscular fibres, which run across the extended muscular mem- 
brane. It is evident that when the parts are replaced so as to 
form a cylinder, this narrow fasciculus will form a ring in it. 
Thus arranged the circular fibres can readily close the lower ori- 
fice of the stomach. 

The pylorus separates the stomach from the intestine duode- 
num ; and this separation is marked exteriorly by a small circu- 
lar depression, which corresponds exactly with the situation of 
the pylorus. 

The arteries of the stomach are derived from the Caeliac, the 
first branch which the aorta sends off to the viscera of the ab- 
domen. This great artery, immediately after it leaves the aorta, 
is divided into three branches, which are distributed to the sto- 
mach, the liver, and the spleen, and are called the Superior Coro- 
nary or Gastric, the Hepatic and the Splenic. Besides the first 



LYMPHATICS AND NERVES OF THE STOMACH. 4 J 

mentioned branch, which is distributed principally to the neighs 
bourhood of the cardia and to the lesser curvature, the stomach 
receives a considerable branch from the hepatic, which passes 
along the right portion of its great curvature, and has been call- 
ed the right gastroepiploic, and another from the spleen, which 
passes along the left portion of the great curvature, and has been 
called the left gastro-epiploic. In addition to these branches, 
the splenic artery, before it enters the spleen, sends off several 
small arteries to the great extremity of the stomach, which are 
called vasa brevia. 

These vasa brevia generally arise from the main trunk of the 
splenic artery, but sometimes from its branches. 

The veins which receive the blood from these arteries have 
similar names, and pursue corresponding courses backwards : 
but they terminate in the vena portarum. 

The absorbent vessels of the stomach are very numerous and 
large: they pass to the glands which are on the two curvatures, 
and from thence to the thoracic duct. It is an important fact 
relative to the history of digestion, that there are good reasons 
for doubting whether chyle commonly passes through them, 
notwithstanding their number and size.* 

The nerves of the stomach are derived from the two great 
branches of the par vagum, which accompany the oesophagus 
and are mostly spent upon this organ, and form branches from 
several plexuses, which are derived from the splanchnic portions 
of the intercostal nerves. 

— The par vagum nerves form a plexus round the cardiac 
orifice, and are distributed, the left on the anterior, and the right 
on the posterior face of the stomach. 

— These nerves can be traced into the muscular coat of the 
stomach, and some of them as far as the duodenum, 
— The section of these nerves, paralyzes the muscular coat of the 
stomach. These nerves serve to connect the stomach, function- 
ally, to the oesophagus, to the pharynx, larynx, lungs and heart, 

* Sabaticr, however, in one subject observed white lines on the stomach, which 
he suspected to be Jactcals. Sec his account of the absorbents of the stomach. 



42 THE INTESTINES. 

The nerves which the stomach receives from the plexuses of 
the abdomen, in like manner connect it with the abdominal 
viscera. — 

Of the Intestines. 

The intestines form a continued canal from the pylorus to the 
anus, which is generally six times the length of the subject to 
which they belong.* Although the different parts of this tube 
appear somewhat different from each other, they agree in their 
general structure. The coats or lamina of which they are com- 
posed, are much like those of the stomach, but the peritoneum 
which forms their external coat does not approach them in the 
same manner ; nor is it continued in the form of omentum from 
the whole tube, there being only a certain portion of intestine, 
viz. the colon, from which such a process of peritoneum is con- 
tinued. 

The Muscular Coat, like that of the stomach, consists of two 
strata, the exterior of which is composed of longitudinal fibres, 
which adhere to the external coat, and do not appear very 
strong. The other stratum, consisting of circular or transverse 
fibres, is stronger, as the fibres are more numerous. It is ob- 
servable that they adhere to the longitudinal fibres; and they 
seldom, if ever, form complete circles. 

The cellular substance immediately within the muscular fibres 
resembles the nervous coat of the stomach in its firmness and 
density. It is likewise so arranged as to form many circular 
ridges on its internal surface, which support to a certain degree 
the permanent circular plaits of the internal coat, called valvulse 
conniventes. 

* This is a rule a long time admitted among anatomists, making the small in- 
testines twenty-four to twenty-eight feet in length, and the large intestines about 
six more. But this mode of measurement is found to be totally defective when ap- 
plied to comparative anatomy, and Dr. Horner has found it applicable only to man, 
when the intestine is left attached to the mesentery ; for, as he observes, " if it be 
cut oiF and straightened, the small intestine will measure thirty-four feet, which, 
added to the eight feet which the large intestine measures when treated in the same 
way, will amount in all to forty-two feet. If to the estimate of this length are 
added what is lost by the doubling of the mucous coat, the entire length of sur- 
face must amount to nearly sixty feet, at least in many subjects." — p. 



LIEBERKUHN ON THE VILLOUS COAT. 43 

The inner surface of the internal coat has been commonly 
compared to that of velvet, and the coat is therefore called vil- 
lous ; but there is certainly a considerable difference between 
these surfaces ; for if a portion of the small intestine be inverted, 
and then suspended in perfectly transparent water, in a clear 
glass, and examined with a strong light, it will appear like the 
external surface of the skin of a peach, on which the down or 
hair-like processes are not so close as those on velvet. On this 
surface, between the villi, there are many orifices of mucous fol- 
licles and of exhaling vessels.* Exterior to the villous coat, 
many very small glandular bodies are sometimes found, which 
are called after their describers Glandulae Brunneri and Peyeri. 

The internal coat of the upper portion of the interstitial tube 
is arranged so as to form a great number of transverse or circu- 
lar folds or plaits, called Valvules Conniventes, which do not 
generally extend round the intestine, but are segments of circles ; 
they are so near each other, that their internal edges, which are 
very movable, may be laid upon the folds next to them, like 
tiles or shingles. It is evident that this arrangement of the in- 
ternal coat must add greatly to its length. This coat is ex- 
tremely vascular, so that in the dead subject it can be uniformly 
coloured by a successful injection. The minute structure of it 
has been the subject of very diligent inquiry. There can be no 
doubt but that an immense number of exhaling and of absorbent 
vessels open upon it; but there are many different opinions re- 
specting the termination of one set of vessels and the commence- 
ment of the other 

A very interesting account of the Villous Coat was published 
in 1744, by Lieberkuhn, who was considered by his contempo- 
raries as a most expert practical anatomist, and was also very 
skilful in microscopical examinations, for which he was particu- 
larly calculated, as his natural powers of vision were uncom- 

* It appears clearly, from the account of Lieberkuhn, that the orifices or termi- 
nations of the arteries on the intestines, are distinct from the follicles ; for he 
forced injections from the arteries into the cavity of the intestines, and found the 
follicles still filled with mucus. He then urged the injection further, and filled the 
follicles, or forced the mucus out of them. 



44 HEWSON AND OTHERS ON THE VILLI. 

monly strong. In his essay he refers to his preparations, which 
were at Berlin, and which appear to have excited great surprise 
in the minds of the members of the Academy of Sciences of 
Prussia, at a time when one of the first anatomists of Europe, the 
celebrated Meckel, was of their number. 

According to this account the internal surface of the small 
intestines abounds with villi, and with the orifices of follicles. 
These villi, are about the fifth part of a line in breadth. In each 
of them is a cavity filled with a soft spongy substance, which 
has one or more orifices communicating with the intestines, and 
from which also proceeds a lacteal vessel. On the membrane 
which forms this cavity, blood-vessels are most minutely rami- 
fied. This cavity he calls an ampullula, and supposes it to 
constitute the principal part of the villus. By injecting the 
arteries of the intestine, he was able to pass a fluid through the 
ampullula into the cavity of the gut ; he kept a stream of air in 
this way passing through the ampullula until it was nearly dry 
and stiff, and then laid it open with a fine instrument. From the 
appearances which then presented, he inferred that the cavity of 
the ampullula was occupied with a spongy or cellular substance. 
Around each villus he found a number of mucous follicles, which 
often were filled with a tenacious mucus: and distinct from 
these must be the exhalent orifices, which discharged a fluid 
injected by the arteries without passing through the mucous fol- 
licles. 

Lieberkuhn died early, and left but one essay on this subject, 
which was originally published in Holland, in 1744, but has been 
republished by the Academy of Berlin, in their Memoirs ; and 
also by Mr. John Sheldon, of London. 

This account of Lieberkuhn appears to have been admitted by 
Haller : but it has been rigidly scrutinized by some of the anato- 
mists of London, who were particularly interested with the sub- 
ject ; as they had paid great attention to the absorbent system, 
and were very successful in the investigation of it. 

The late Mr. Hewson, whose opinion is entitled to the 
greatest respect, rejected the idea of the ampullula, and believed 
that the villi are composed of net-works of lacteals, as well as 



FYFE AND OTHERS ON THE VILLI. 45 

arteries and veins; although he added that "this is the only cir- 
cumstance concerning these parts in which he should differ from 
this very acute observer."* 

Mr. Sheldon agrees with Lieberkuhn: but Mr. Cruikshank 
asserts, that, " in some hundred villi, he has seen the lacteals 
originate by radiated branches, whose orifices were distinct on 
the surface of the villus." The villus being transparent, when 
the intestine was immersed in water, these branches, filled 
with chyle, could be seen passing into the lacteal. Mr. Cruik- 
shank therefore supposes that Lieberkuhn was mistaken, and 
that the spongy cavity, or ampullula, was the common cellular 
membrane, connecting together all the arteries, veins, nerves, 
and lacteals. 

It seems probable, from Mr. Cruikshank's statement, that Dr. 
William Hunter held the same opinion with himself. And there 
is also reason to believe that Monro the second, who studied 
anatomy at Berlin, held a different opinion from Lieberkuhn. 

Mr. Fyfe, who has been much employed in the investigation 
of the absorbent system, and must be perfectly acquainted with 
the preparations of Monro, asserts that each lacteal takes its 
rise upon one of the villi by numerous short radiated branches, 
and each branch is furnished with an orifice for imbibing chyle. 

Several of the late French writers adopted the opinion of 
Lieberkuhn ; but his countryman Soemmering gives a different 
account of the subject. He says, that, besides the blood-vessels, 
each villus consists of a fine net-work of absorbent vessels, 
whose orifices may be distinctly recognised ; and that from six 
to ten of these orifices are sometimes discovered. 

Mascagni, who has published the most extensive work upon 
the absorbent system that has yet appeared, supposes Lieberkuhn 
to have been mistaken, and confirms the description of Hewson : 
but he also agrees with Hewson in his opinion of the general 
accuracy of Lieberkuhn. 

Notwithstanding their differences respecting the origin of the 
lacteals, all these observers have agreed, that the orifices which 

* See Hewson's Experimental Inquiries, vol. 2, page 171. 



4 g DIVISION OF THE INTESTINES. 

communicate with the lacteals are on the villi ; and that these 
villi contain also very fine ramifications of blood-vessels. They 
have also agreed that the surface of the intestines in the intervals 
of the villi seems occupied with the orifices of ducts or of exha- 
lent vessels.* 

Division of the Intestines. 

Although there is a considerable degree of uniformity in the 
structure of the intestinal canal, different parts of it are very 
distinguishable from each other by their exterior appearance, by 
their size, their investments, and their position. 

The first division is into two great portions, which are very 
different from each other in their diameter and length, as well as 
their situation ; the first portion being much smaller in diameter, 
and near four times the length of the other. 

These portions are therefore known by the names of Great 
and Small Intestines, and the line of separation between them is 
very strongly marked; for they do not gradually change into 
each other, but the alteration in size and in exterior appearance 
is very abrupt, and their communication is not perfectly direct. 
A considerable portion of the Great Intestine is fixed immovably 
in the abdomen, while a large part of the Small Intestine is very 
movable. 

Each of these great portions of the intestinal tube is subdi- 
vided into three parts. Thus, in the Small Intestine, there is a 
piece at the commencement called Duodenum, a great part of 
which has no coat from the peritoneum, and is immovably 
fixed in one situation ; while all the remainder of the small intes- 
tine has a uniform covering from the peritoneum, and is very 
movable. This last piece, notwithstanding its exterior uniform- 
ity, is considered as forming two parts. The uppermost two- 

* On this subject the student will consult with advantage, Hewson's Experi- 
mental Inquiries, vol. 2; Sheldon's History of the Absorbent System, part 1st; 
Cruikshank on the Anatomy of the Absorbing Vessels; and the Historia Vasorum 
Lymphaticoruin Corporis Humani, of Mascagni. 

—The more recent investigations of Beclard, Meckel, Breschet, Miiller, Dr. 
Horner and others have a tendency to disprove the existence of absorbing orifices 
on the surface of the villi; vide, Absorbent System. — p. 



THE SMALL INTESTINES. 47 

fifths from one part, which is called Jejunum ; and the remainder 
is called Ileum. The Great Intestine commences in the lower 
part of the right side of the abdomen, and after proceeding up 
that side, crosses over to the left, along which it descends to the 
lower part again, when by a peculiar flexure it proceeds to the 
centre of the posterior margin of the pelvis, from which it passes 
down to the anus. A short portion of this intestine, which is 
above its junction with the ileum, is called Cescum ; the part 
which proceeds from this, round the abdomen, is called Colon ; 
and the portion which is in the pelvis is called Rectum. 

Of the Small Intestines. 

Previous to the description of the small intestines, it is neces- 
sary to observe, that the Mesocolon, or process of the peritoneum 
connected to the transverse portion of the colon, forms a kind of 
movable and incomplete septum, which divides the abdomen 
into an upper and lower apartment. Above this septum are the 
stomach, with the commencement of the duodenum, the liver, 
and the spleen ; below it, that portion of the small intestine 
which is called jejunum and ileum, makes its appearance. The 
portion of the intestine which passes from the stomach to the 
jejunum, and is called Duodenum, is so much involved by the 
mesocolon, that the greatest part of it cannot be seen without 
dissecting the mesocolon from its connexion with the back of the 
abdomen. — For the duodenum proceeds backwards from the 
pylorus, and passing down behind the peritoneum, enters a 
vacant space between the two lamina of the mesocolon; it pro- 
ceeds for some distance in this space, and then emerges on the 
lower side of the mesocolon. Here the duodenum terminates, 
and the small intestine then is invested by the peritoneum in such 
a manner as to form the mesentery, which continues with it 
throughout its whole course to the great intestine. This portion 
of the intestine, although very uniform in its exterior appear- 
ance, as has been observed before, is divided into Jejunum and 
Ileum: the jejunum being the upper portion, which begins at the 
mesocolon ; and the ileum the lower portion, which opens into 
the crcat intestine. 



4g DUODENUM. 

Of the Duodenum. 

The length of this intestine is equal to the breadth of twelve 
fingers, and hence its name. It is very different from the rest 
of the small intestine, not only as respects its position and invest- 
ment by the peritoneum, but on account of its connexion with 
the liver and pancreas, by means of their excretory ducts, which 
open into it. From this connexion with these glands, probably, 
all the peculiarities of its position are to be deduced. 

When the stomach is in its natural situation, the pylorus is at 
some distance from the back of the abdomen. The duodenum 
proceeds backwards from this point, and passes near the neck of 
the gall-bladder, being here connected with the small omentum ; 
it then curves downwards, and descends before the right kidney, 
sometimes as low as the lower part of it ; then it curves again, 
and passes over to the left: after it has arrived at the left side of 
the spine, at the second or third lumbar vertebra, it projects for- 
wards and downwards to form the jejunum. The only portion 
of this intestine which is movable, is that which is in sight as it 
proceeds immediately from the pylorus, being about an inch and 
a half, or two inches in length. The remainder is connected to 
the back of the abdomen, and lies between the two lamina of the 
mesocolon. In its progress it passes before the aorta and the 
vena cava, but the principal branch of the vena portarum is be- 
fore it. 

The duodenum is larger in diameter than any other part of 
the small intestines, and has a stronger muscular coat. Its 
general situation admits of great dilatation, and it has been 
called a second stomach, (ventriculus succenturiatus.) Its inter- 
nal coat is strictly villous in the anatomical sense of the word ; 
and its folds, the valvule conniventes, begin at a small distance 
from the pylorus. The orifices of many mucous ducts are to be 
seen on its surface. It is supposed that some of these are the 
terminations of ducts from the glands of Brunner, which some- 
times appear in the villous coat, or very close to it exteriorly ; 
being small flat bodies, with a depression in the centre, and a 
foramen in the depression. They are sometimes very numerous 



JEJUNUM AND ILEUM. 49 

at the upper extremity of this intestine, and diminish gradually 
towards the other extremity. 

The biliary and pancreatic ducts open posteriorly into the 
duodenum, rather above the middle of it. The orifice of these 
ducts is generally surrounded by a small tubercle, which is ob- 
long, somewhat rounded at one extremity, and pointed at the 
other. Sometimes this orifice is in a plait, like one of the val- 
vula3 conniventes- Most commonly the two ducts unite before 
they perforate the coat, so as to form but one orifice ; and some- 
times they open separately, but always very near to each other. 

Absorbent vessels, which contain chyle, are found on the 
duodenum. 

The Jejunum and Ileum 
Are situated in the abdomen very differently from the duo- 
denum. When the cavity is opened, and the omentum raised, 
they are in full view; and every portion of them except the two 
extremities and the parts near them, can readily be moved. 
This freedom of motion is owing to the manner in which they 
are invested by the peritoneum ; or, in the technical language of 
anatomy, to the length of their mesentery. They agree in their 
structure with the general description of the small intestines, but 
their muscular coat is rather weaker than that of the duodenum. 
The valvulee conniventes are very numerous and large in the 
upper part of the tube, or jejunum ; and gradually diminish in 
number, until they finally disappear in the lower part of the ileum. 
The villous coat is in perfection in the jejunum, the villi being 
more conspicuous there than in any other part of the intestinal 
tube. There are frequently found, exterior to this coat, but 
intimately connected with it, many small glandular bodies of a 
roundish form, which are often clustered together at that part of 
the intestine which corresponds with the interstice of the lamina 
of the mesentery. They are called Peyer's glands, after the 
anatomist who first described them ; and are supposed, like the 
glands of Brunner, to secrete mucus. If a portion of the jejunum 
be inverted, and moderately distended with air, these bodies 
appear very distinctly in it, dispersed at small distances from 

VOL. II. 5 




50 MESENTERY. 

each other. In the ileum they appear in small clusters, which 
often have the appearance of disease. 

No natural line of separation for distinguishing the jejunum 
and ileum from each other, is to be found ; but these names are 
still retained ; and, therefore, a rule laid down by Winslow is 
generally adopted, viz. to name the first two-fifths of the tube 
jejunum, and the remainder ileum. There are, however, some 
important differences between these portions of the intestine. 

In the jejunum, the valvulae conniventes are so numerous, that 
they lie in contact with each other, as shingles on the roof of a 
house; in the ileum they gradually diminish in number, and 
finally disappear. In the jejunum, the villi are much stronger 
than they are in the ileum. 

It is very difficult to acquire a precise idea of the arrangement 
of this part of the intestinal tube, while it is in the abdomen, 
especially if it be much distended; but if it be separated at each 
extremity from the intestine with which it is connected, and the 
mesentery cut off from the back of the abdomen, and the whole 
then spread out upon a flat surface, it will appear, as has been 
already said, that the intestine is arranged so as to form a semi- 
circle, or large curve; the concavity of which is opposite to the 
back of the abdomen, while the convexity presents forward. It 
will also appear, when thus placed upon a table, that the intestine, 
while connected with the mesentery, is laid into many folds. It 
has been supposed, that the middle portion of the mesentery, and 
the intestine connected with it, is generally in the umbilical re- 
gion ; and the two portions on the sides of it are in the iliac 
regions; but their situation in the abdomen varies considerably 
at different times. When the viscera of the pelvis are empty, a 
large portion of the small intestine is in the pelvis ; but when 
those viscera are filled, the intestine is in the general cavity of 
the abdomen. 

The Mesentery 

Is a process of the peritoneum, which is formed in the manner 
of a plait or fold, and of course consists of two lamina. These 
lamina proceed from the back part of the abdomen, and are so 



MESENTERY. 



51 



near to each other, that the}' compose one substantial process ; 
having cellular and adipose substance, blood-vessels and nerves, 
with absorbent or lacteal vessels and their glands between them. 
The form of this process, when it is separated from the back, 
and the intestines are detached from it, is somewhat semicircular; 
that portion of its margin or edge which corresponds to the dia- 
meter of the semicircle, is connected to the back of the abdomen, 
and called the root of the mesentery; the edge, which is the 
circumference of the semicircle, is connected with the intestine. 
The edge connected with the back of the abdomen is commonly 
about five or six inches in length : the semicircular edge, instead 
of extending fifteen or eighteen inches, the ordinary proportion, 
is attached to a portion of intestine sometimes twenty-four feet 
in length. The mesentery, on account of this great difference 
between its diameter and circumference, has been compared to 
the ruffle of a shirt sleeve ; its roots being taken for the plaited 
edge of the ruffle, and the circumference for its loose edge. But 
the comparison is not precisely accurate ; for the mesentery is 
not plaited at its root, but perfectly smooth, and free from every 
kind of fold. It begins to enlarge towards its circumference* 
and enlarges to that degree that it falls into plaits or folds : pre- 
cisely such as would exist in a semicircular piece of membrane 
about six inches in diameter, if a number of simple incisions, of 
about an inch and a half in length, were made in a radiated 
direction from the circumference, and if portions like a sextant 
or quadrant were taken from a circular membrane three inches 
in diameter, and united by their edges to these incisions, so that 
their circumference might be continuous with the circumference 
of the large semicircular piece. In this case, the portions like 
quadrants or sextants would assume a folded position like the 
edge of the mesentery, while the middle of the semicircular piece 
would preserve its regular form without folds; as is the case 
with the mesentery at some distance within its circumference. 
By many additions of this kind, the circumference of a mem- 
brane, which was originally a semicircle of five or six inches, 
may be extended so as to exceed greatly that of the mesentery 
It seems of course impossible to form an accurate model of the 



52 MESENTERY. 

mesentery with a single piece of membrane or paper; but it may- 
be easily made with clay, or any ductile substance. A model of 
this kind must necessarily be folded after the manner of the 
mesentery; and its circumference, like the mesentery, would 
appear as if formed of portions of the circumference of smaller 
circles united to each other.* 

The root of the mesentery commences with the jejunum on 
the lower side of the mesocolon, at the left of the spine, and ex- 
tends downwards near to the right iliac region, crossing the spine 
obliquely. When it is examined in its natural situation, the peri- 
toneum is found continued from the back of the abdomen to the 
intestine; it then surrounds the intestine, and continues from it to 
the back of the abdomen again. There must therefore be two 
lamina of peritoneum in the mesentery, and there must be a small 
portion of intestine answering to the interstice between these 
lamina which is not covered by the peritoneum. The blood- 
vessels, and absorbents, or lacteals pass most commodiously to 
the intestines between these lamina; for they are connected with 
large trunks that lie on or near the spine, and the root of the 
mesentery commences there. 

The glands connected with the lacteals or absorbents are very 
conspicuous in the mesentery, and are commonly called mesen- 
teric glands. They are of different sizes, from more than half 
an inch to one or two lines in diameter. They are very nume- 
rous, and scattered irregularly, but are seldom observed very 
near to the intestine. They are often enlarged in consequence of 
disease, especially in children. 

The nerves of the small intestines which are derived princi- 
pally from the superior mesenteric plexus, are also to be found 
here. 

The adipose matter between the lamina of the mesentery is 
very often in large quantity, but varies, in proportion to the ge- 
neral quantity of adeps in the subject. 

* A model, upon the plan first mentioned, was invented by Dr. J. G. Shippen. 
It has been proposed, I believe by M. Gavard, to make one with a single piece of 
buckskin, of a semicircular form, by stretching it at the circumference. 



LARGE INTESTINES. 53 

OF THE GREAT INTESTINES. 

The Ccecum and Colon 

Are very different from the small intestines in many respects. 
They are much larger in diameter; their external surface is 
marked by three longitudinal bands of light colour, which ex- 
tend the greatest part of their length, and are placed nearly at 
equal distances from each other ; the spaces between these 
bands are marked by transverse indentations, which pass from 
one band to the other, at short but unequal distances. At these 
indentations the coats of the intestine are pressed inwards, as if 
a fine thread had been drawn round it externally, while the 
spaces between them are full and tumid, and on this account are 
called cells. 

The great intestine, with these appearances, begins, as has 
been already observed, in the right iliac region, by a rounded 
end which rests on the fossa or concave surface formed by the 
costa of the ileum ; from this it is continued upwards in the 
right lumbar region, anterior to the kidney, called ascending co- 
lon, until it arrives near the liver, when it forms a curve, called 
the arch of the colon, and passes directly across the abdomen to the 
left side. In this course it approaches so near to the under side 
of the liver, that it is often in contact with it, and with the gall- 
bladder, which, after death, tinges it with a yellow colour. On 
the left side it passes down the lumbar region, forming the de- 
scending colon, before the kidney, to the left iliac region ; here 
it is curved so as to resemble the Roman letter S, inverted, 
called the sigmoid flexure ; this curve generally carries it to the 
right side of the spine, and then brings it back to the centre of the 
sacrum. Here the intestine changes its course, and passing into 
the pelvis, continues downward, in contact with the sacrum and 
coccyx, and partaking of the curvature of those bones, until it 
terminates at the anus, where it is connected with the sphincter 
and levator ani muscles. 

About two inches from the commencement of the great in- 
testine, the ileum opens into it laterally ; and all that portion 

5 * 



54 cjccum. 

which is between its commencement and the insertion of the 
ileum is termed Cacum, or the blind intestine : that part of the 
great tube, which is included in its course from the insertion of 
the ileum to the posterior part of the brim of the pelvis, is called 
Colon ; and the remainder, or the part which is contained in the 
pelvis, is termed Rectum. 

The Ccecum is nearly as wide as it is long ; it is fixed in the 
right iliac fossa by the peritoneum, which invests it so that the 
great body of the intestine projects from the surface of the fossa 
covered by the peritoneum ; but a portion is in close contact 
with the surface, and connected to it by the cellular membrane. 
Its external surface covered by the peritoneum, is marked by 
two of the bands or stripes before mentioned, which proceed on 
it lengthways. These bands are in full view, but the third band 
is generally on that part of the intestine which rests on the iliac 
fossa, and is therefore out of sight. At the rounded extremity 
of the caecum, situated anteriorly and internally, is a small pro- 
cess resembling an earth-worm in form and size : this is therefore 
called, Appendicula Vermiformis. It is hollow, and communi- 
cates with the cavity of the cascum, has its other extremity 
closed up. It is composed of the same number of coats and has 
the same structure as the great intestine: its length varies from 
two to four inches. 

— After the stomach, the cascum may be considered the largest 
portion of the intestinal canal. 

— In the foetus its diameter appears to be nearly the same as 
that of the adjoining part of the colon, and its subsequent in- 
crease in diameter over that of the colon, appears to be mainly 
owing to the stagnation of the faecal matters, in consequence of 
the dependent position of this part of the large intestine, and the 
transverse direction by which the contents of the ileum are dis- 
charged into it. 

— The caecum varies much, however, in different persons, in re- 
gard to its length as well as its diameter. 

— Retentions of the faecal matter often take place in it, in cases 
of constipation, which have frequently been mistaken for inflam- 
mation of the bowels. — 



COLON. 55 

The longitudinal bands above mentioned commence at the 
junction of the appendix with the caecum, and continue through- 
out the extent of the colon. They appear to be formed by some 
of the longitudinal fibres of the muscular coat, which are ar- 
ranged close to each other. These fibres seem to be shorter 
than the coats of the intestine, and the interior coats adhere 
firmly to them. Thus are produced the indentations and cells ; 
for if the bands are divided transversely, the indentations disap- 
pear, and the surface of the intestine becomes uniform. One of 
these bands is covered by the mesocolon.* 

The circular or transverse fibres of the muscular coat of the 
ccccum and colon are very delicate, and not numerous. 

The internal coat differs materially from that of the small in- 
testines, although at first view they seem to resemble each other; 
for if a portion of the ileum and of the colon be inverted and 
suspended in water, no villi can be seen with the naked eye on 
the internal coat of the colon, while those of the ileum are very 
visible. The glands exterior to this coat are larger than those 
on the small intestines. 

Instead of valvulse conniventes, are the ridges made by the 
indentations or depressions above described, which separate the 
incomplete cells from each other. These ridges differ essen- 
tially from the valvulae conniventes, because all the coats of the 
intestine are concerned in their formation, whereas the valvules 
conniventes are formed by the villous coat only : they also pro- 
ject into the cavity of the intestine, while the valvulae are laid 
on its surface. They pass only from one longitudinal band to 
another, and, in consequence of this, the cells are small, and the 
position of each band is very evident when the intestine is laid 
open. 

The communication of the ileum with the great intestine has 
been already stated to be on the left side of it, about two inches 
from its commencement. The aperture is so constructed, that 

* In the foetus, no cells are visible in the colon. Their developement appears 
to be owing to the growth of the longitudinal fibres not taking place so rapidly in 
regard to length, as that of the other coats; which necessarily causes the crimping 
of the latter into folds, and the formation of cells. — p. 



50 COLON. 

it is considered as a valve, and is called the valve of Bauhin, or 
of Tulpius, after the anatomists who have described it.* The 
appearance of the aperture is as follows : If the cascum, with a 
small portion of the ileum and of the colon may be separated 
from the other intestines, and kept in an inflated state until it be 
so dry as to preserve its form when opened, and then if the 
cascum and colon be laid open opposite to the aperture of the 
ileum, a large transverse ridge, resembling some of the ridges or 
folds just described, will be seen projecting into the cavity of the 
intestine. In the internal edge of this fold is a long slit or open- 
ing, which forms the communication between the two intestines. 
It is obvious that the form of this fold must be that of a crescent ; 
and that its two surfaces with the slit between them, must have 
the appearance of two lips, which would readily permit a fluid 
or substance of soft consistence to pass from the ileum into the 
great intestines, but must impede, if not prevent, its passage 
back ; especially if the large intestines were distended, as then 
the lips would be pressed against each other. 

When the peritoneal coat is dissected from each of the intes- 
tines at their place of junction, and this structure is then examined 
from without, it appears as if a transverse or half circular indent- 
ation had been formed by the villous coat of the great intestine, 
and that the internal coat of the extremity of the ileum was 
pressed into this indentation, and united to the internal coat of 
the great intestine which formed it ; while there was a slit both 
in the indentation and in the end of the ileum, which formed a 
communication between the cavity of the great intestine and 
the ileum. The longitudinal fibres of both intestines, as well as 
their external coats, seemed to be united, so as to form a com- 
mon cover for them ; while the circular fibres were blended in 
the two portions of the indentation which form the lips of the 
orifice. 

This orifice is, of course, transverse with respect to the in- 
testine. It has been observed, that there was a difference in 

* Posthitis in 1566; Vidus Vidius about 1569; Alberti in 1581 ; and Varolius, 
who died 1575, each lay claims to the discovery of it. Bauhin's claims arc in 
1579.— h. 



POSITION OF THE RECTUM. 



57 



the thickness and strength of the two lips or valves; that the 
lower valve was the strongest and appeared to have the largest 
proportion of muscular fibres in its composition. At the extre- 
mities of the orifice, and near each end of the fold or ridge, ar# 
tendinous fibres, and which give strength to the structure : they 
are called the Retinacula of Morgagni, as they were first de- 
scribed by that anatomist. 

There is a great reason for believing that this valve cannot pre- 
vent the retrograde motion of the contents of the intestines in all 
cases ; for in some instances of hernia and of colic, matter per- 
fectly stercoraceous has been vomited, and the probable infer- 
ence from such a state of the ejected matter is, that this matter 
has been in the large intestines. It is also said, that supposito- 
ries and enemata have been discharged by vomiting. 

On the right and left sides of the abdomen, the colon is in 
close contact with the posterior surface of the cavity. The 
peritoneum which covers this surface extends over the intestine 
also, and thus retains it in its position, The great arch of the 
colon, which is loose and moves far from the back of the abdo- 
men, is invested by the two lamina of the omentum, which, after 
surrounding it, unite again and form the mesocolon. Connected 
with the exterior surface of the colon are many processes, com- 
posed of adipose membrane, varying in length from half an 
inch to an inch and a half: these appear to be of the nature of 
the omentum, and are therefore generally denominated Appen- 
dices Epiploic ce. 

The Rectum. 

After forming the sigmoid flexure, the colon terminates ; and 
the rectum begins opposite to the lower surface of the last lum- 
bar vertebra, and nearly in contact with it; from this it proceeds 
downwards, forming a curve like the sacrum, until it terminates 
at the anus ; where it is invested with the muscles called the 
sphincter and levator ani. It is called rectum, because in this 
course it is supposed not to incline to either side ; but it is often 
found on one side of the middle line.* 

* Morgagni and Haller supposed it to be commonly on the left of the middle 
line, and Sabatier on the right. 



gg STRUCTURE OF THE RECTUM. 

This intestine being in contact with the posterior surface of 
the pelvis, is covered, on its anterior surface only, by the perito- 
neum which lines the posterior surface of the pelvis; and it is 
fixed in this situation by the peritoneum, as the colon is on the 
right and left sides of the abdomen, but more loosely ; and, there- 
fore, the term Mesorectum has sometimes been applied to that 
portion of the peritoneum which is analogous to the mesentery 
and mesocolon. The peritoneum does not extend to the end of 
the rectum ; for it is reflected at the lower part of the pelvis 
from the rectum to the bladder, or uterus, and does not line the 
bottom of the pelvis ; so that the lower part of this intestine, as 
well as of the other viscera of the pelvis, is below the peritoneum, 
and not connected with it. 

The muscular coat of the rectum is much thicker and stronger 
than that of any other intestine. The strata of longitudinal and 
circular fibres which compose it are very distinct from each 
other. The longitudinal fibres are most numerous, and termi- 
nate at the insertion of the fibres of the levator ani muscle. 

The lower circular fibres are intimately connected with the 
sphincter ani. 

— The circular muscular fibres at the end of the rectum, are 
so thickened as to form a sort of annular muscle, which projects 
into the cavity of the intestine, like the pylorus of the stomach. 
It is attached to the proper sphincter muscle below, by cellular 
tissue, and like it and the muscles of the pharynx at the other 
extremity of the canal, is in a great measure under the control 
of the will, being supplied in part with nerves from the cerebro- 
spinal system. It aids the sphincter in retaining the fasces in the 
pouch of the rectum. 

— The three longitudinal muscular bands of the colon at the 
lower edge of the sigmoid flexure, separate into fasciculi, which 
are distributed as they descend round the circumference of the 
intestine, and form a thick uninterrupted layer round the rectum. 
The longitudinal fibres of the rectum have been shown by 
Professor Horner, to terminate in delicate tendons, which pass 
between these two sphincter muscles, internal and external, and 
turn upwards and inwards to be inserted on the inner face of the 



STRUCTURE OF THE RECTUM. gg 

mucous membrane of the rectum. Opposite the lower edge 
of the internal sphincter, the mucous membrane is thrown into 
a number of plaits or folds, in which the same anatomical 
observer has pointed out a number of irregular valvular pouches 
which open upwards. These when diseased become a source 
of intolerable itching and irritation, which attracted the atten- 
tion of Dr. Physick, who was in the habit of relieving the suf- 
fering they produced by their excision.* 

The internal coat is very vascular, but the villous structure is 
not apparent. Mucous follicles are also very numerous; and 
there are likewise some distinct glandular bodies exterior to this 
coat, which vary in size in different subjects. 

— The mucous membrane of all the large intestines, when ex- 
amined with the microscope under water, present scarcely any 
appearance of villi, but exhibit every where, slight honey-comb- 
like depressions, somewhat analogous to those of the stomach. 
It is strewed with a multitude of follicles, {tanquam Stella; firma- 
mente, Peyer,) depressed and perforated in their centre, as seen 
in Fig. 47, p. 69 ; and which in many subjects, especially old 
men, present at their orifices the appearance of black spots. — 

The quantity of mucus discharged from the rectum in certain 
cases of disease, is sometimes very great. The internal coat, in 
consequence of the contraction of the circular fibres exterior to 
it, sometimes forms longitudinal folds, which have been called 
its columns ; these often disappear when the intestine is opened 
lengthways and spread out. By the contraction of the longitu- 
dinal fibres, the internal coat is often thrown into folds or dou- 
blings, that must assume a transverse or circular direction ; they 
occasionally pass down through the sphincter, and form the pro- 
lapsus ani. The rectum is most plentifully supplied with blood- 
vessels, to be described hereafter ; and it may be observed, that, 
on the lower part of the internal coat, the veins are particularly 
numerous.f 

* For an excellent account of these parts, see article Anus, by Dr. R. Coates, in 
the American Cyclopedia of Med. and Surg-. Philadelphia. — p. 

t No intestine in proportion to its size, receives so much blood as the rectum, 
and the veins at its lower part not unfrequently exist in the form of a plexus. — p. 



60 ABSORBENTS AND NERVES OF THE INTESTINES. 

The internal coat of the rectum terminates abruptly just within 
the anus, and is united to a production of the skin, which, like 
the covering of the lips, is very delicate and vascular, and has 
an epithelium, or very thin cuticle, spread over it. The levator 
and sphincter ani muscles, with which the termination of the 
rectum is invested, are described in the first volume. 

The Absorbents of the Intestines, are commonly denominated 
Lacteals* They originate on the internal surfaces of these vis- 
cera, as has been already described. After passing through 
the lymphatic glands, which are so numerous on the mesentery, 
they generally unite and form one of the great trunks which 
compose the thoracic duct. It is asserted, that some of the ab- 
sorbent vessels of the lower intestines unite to the lymphatics of 
the loins. 

The Nerves of the Intestines are principally derived from the 
intercostals, or great sympathetics. From each of these nerves, 
while they are in the thorax, an important branch, called the 
ramus splanchnicus, arises. These splanchnic branches pass 
through the diaphragm, and are the chief contributors to the 
ganglions and plexus formed in the abdomen. A plexus derived 
from this source surrounds the superior mesenteric artery, and 
another the inferior mesenteric ; and from these proceed the 
nerves of the intestines. 

The Omentum 

Requires a separate description, although several circum- 
stances connected with its structure have been already noticed. 
It often varies in its position ; but when it is rendered firm by a 
quantity of adipose matter, it is spread over the intestines like an 
apron, extending from the lower edge, or great curvature of the 
stomach, towards the bottom of the abdomen. 

As has been already said, it is an extension of the peritoneum, 
in two lamina, from the concave surface of the liver to the lesser 

* The Lacteals were first observed by Erasistratus and Herophilus, of the school 
of Alexandria, during the reign of the Ptolemies; and subsequently by Aselli, of 
Pavia, in 1622, the knowledge of them having been lost for 1900 years.— h. 



OMENTUM. 



61 



curvature of the stomach ; and these lamina, after surrounding 
the stomach, come in contact with each other near its great 
curvature. From this portion of the stomach, from the com- 
mencement of the duodenum, and also from the spleen, the 
Omentum, composed of two lamina, descends over the colon and 
the small intestines more or less low into the abdomen; it is then 
folded backwards and upwards, and is continued until it meets 
the great arch in the colon : here the lamina again separate and 
enclose that portion of the intestine, on the posterior side of 
which they again approach each other, and form a membrane 
like the mesentery, of two lamina, which passes from the concave 
or posterior surface of the colon to the back of the abdomen, 
where it is continued into the membrane which lines that surface. 
This last portion is the Mesocolon: the portion between the liver 
and stomach is called the Omentum of Winslow, or the lesser 
omentum ; and the great portion between the stomach and colon 
is called the Great Omentum, or the omentum gastro colicum. 
There is also a process of peritoneum continued from that portion 
of the colon which is on the right side of the abdomen, and from 
the caecum, which extends to some distance; it is formed of two 
lamina, that compose a cavity of an angular form. This has 
been called the Omentum Colicum. 

The great and small omentum, with a portion of the peri- 
toneum on the back of the abdomen, form a sac, which encloses 
a distinct cavity in the abdomen. The anterior part of this sac 
is composed of two lamina, and between these lamina are the 
stomach and the great arch of the colon. This cavity formed 
by the two omenta, communicates with the general cavity of the 
abdomen by a foramen of a semicircular form, called the Fora- 
men of Winslow, which is behind the great cord of the vessels 
that go to the liver. 

The omentum is so delicate in structure, that when free from 
fat, it is very liable to laceration, merely by adhering to the 
fingers, if they are dry. Winslow therefore advised that some 
unctuous substance should be rubbed on the hands, before they 
were applied to it. 

The appearance of the great omentum is very different in 

VOL. II. 6 



62 GENERAL ANATOMY OF MUCOUS MEMBRANES. 

different persons. In the emaciated, it appears like a delicate 
transparent membrane : in the corpulent, it is like a broad mass 
of adeps, which sometimes is very thick. When it is thus loaded 
with adeps, it is most commonly spread over the small intestines: 
when it is free from fat, it is often compressed together, so as to 
form a small mass near the arch of the colon, on the left side. 

The principal blood-vessels of the omentum are derived from 
those of the stomach, and are called gastro epiploic arteries 
and veins. 

The use of this membrane in the animal economy has not 
been ascertained with certainty. It seems probable that one of 
its principal objects is to protect the small intestines, and lessen 
the friction consequent upon their motion ; but it has been sup- 
posed to answer several other important purposes.* 

General Anatomy of Mucous Membranes. 

— The mucous membranes form the same sort of lining or 
tegumentary covering to all the cavities of the body that the skin 
does to the exterior ; and the two are continued insensibly into 
one another at the orifices by which these cavities open upon the 
surface. Hence the two are frequently spoken of as the internal 
and external tegumentary systems. The first general and satis- 
factory account of the mucous membranes we owe to Bichat. 
He divided the whole class of mucous membranes into two great 
divisions, the gastro-pulmonary, and the genito-urinary. The 
gastro-pulmonary commences from the mouth, nose, and eyes 
through the lachrymal passages, covers the nasal, buccal and 
pharyngeal cavities, and is prolonged into the salivary ducts, the 
Eustachian tube, the aerial passages and the whole length of the 
alimentary canal, as well as the various secretory ducts which 
open into the latter. 

— The genito-urinary lines the urethra, bladder, ureters, (and 
pelvis of the kidneys in both sexes,) as well as the vagina, uterus, 
and Fallopian tubes of the female, where it opens through the 
peritoneum into the cavity of the abdomen. In the male it is 

• See Halleri Elementa Physiologic, vol. vi. page 381 ; Cavard. Traite de 
Splanchnologie, page 350; and Dr. James Rush's Inquiry into the use of the 
Omentum. 



GENERAL ANATOMY OF MUCOUS MEMBRANES. 53 

prolonged from the bladder into the ducts of the prostate, the 
vesicula seminales, and the vas deferens, to the termination of 
the last in the seminiferous ducts of the testicle. Beneath the 
mucous membrane is a layer of cellular tissue, formerly called 
nervous, which is never seen to contain any adipose matter, and 
is rarely infiltrated with serum. This connects the membrane 
in general to a muscular plane below, as in the alimentary canal ; 
sometimes to an elastic tissue as in many of the excretory ducts; 
and occasionally to the periosteum, as in the nasal cavities. The 
mucous membrane is in general soft and spongy in its charac- 
ter; an appearance which the skin itself presents in many of the 
inferior animals and in very young foetuses. It presents many 
varieties, in different parts of the body. It will be found to di- 
minish successively in thickness as we examine it in the follow- 
ing order; in the gums, the palate, nasal cavities, stomach, 
small and large intestines, gall-bladder, urinary bladder, sinuses 
of the head, and in the excretory ducts: in the last its tenuity 
becomes extreme. The epithelium, or cuticle which is extended 
upon this membrane from the skin covering the lips, terminates 
at the cardiac orifice of the stomach ; that which passes in at 
the anus and vulva, terminates upon the sphincter muscle and 
the lips of the womb. Every where else, the mucous mem- 
branes are covered with a coating or varnish of mucous matter, 
which resembles the epithelium in its chemical composition, and 
seems to be even susceptible of being converted into it, when 
dried and hardened by exposure to the air, as has been observed 
in cases of artificial anus. They vary in different parts in re- 
gard to colour from white to red, passing through all the inter- 
mediate shades. They are red near their points of communica- 
tion with the skin; as in the pharynx and rectum; of a pearl or 
pale rose hue in the stomach; and almost colourless in the centre 
of the intestinal canal, except in cases where they have been 
coloured by disease or by the capillary injection which follows 
asphyxia. 

— The mucous membranes, are thrown in many places into a 
number of loose folds, which amplify very considerably the ex- 
tent of its surface. These folds may be seen in the nasal cavities, 
in the hollow organs in their undistended state, as the stomach 



64 GENERAL ANATOMY OF MUCOUS MEMBRANES. 

and bladder, but particularly in the small intestines, where they 
form an extensive series of permanent folds called the valvules 
conniventes, or valves of Kerkringius. 

—The surface of the membrane presents in many places, a su- 
perficial honey-comb-like appearance, which is discernible only 
after close investigation in the stomach and gall-bladder in man, 
but is strikingly developed in the alimentary canal of our do- 
mestic animals, and in many fishes. 

— All that is known in regard to the chemical analysis of mucous 
membranes, is, that they are insoluble in water, even by boiling, 
but are easy of solution in acids, with which they form a pulp. 
— These membranes, though possessed every where of many 
characteristics common to the whole, vary somewhat in diffe- 
rent parts of the body, especially in regard to their villi and 
their follicles. 

Of the Villi. 

— On the free surface of the mucous membranes are found 
a great number of papillary projections called villi. (See Fig. 
48, page 72.) Each villus is formed of a bundle, which con- 
sists at least of one artery, vein, nerve and absorbent, woven 
together by cellular tissue and covered in by a thinly expand- 
ed fold of the mucous membrane. The villi on the tongue, 
instead of a mucous layer, are covered by the epidermis, (peri- 
glottis,) which is so thick in many quadrupeds, as to constitute a 
hard corneous covering, and convert them into instruments of 
prehension. In the pharynx and oesophagus they hold a sort of 
middle station between those of the tongue and those of the sto- 
mach. The villi of the mucous membrane of the stomach and 
small intestines, are so particularly numerous and so large, com- 
pared with those of the large intestines, bladder and lungs, that 
Gendrin has proposed to call it by distinction the villous mem- 
brane. 

—If we examine, by the aid of a strong glass, the mucous mem- 
brane of the stomach under water, exposed to the strong light of 
the sun, we perceive the whole surface covered by irregular and 
very superficial nipple-like projections and marked by shallow 
grooves passing over the surface of the membrane, so as to give 



OF THE VILLI. 65 

it the appearance somewhat of the intestinal convolutions. 
These nipple-like projections are covered by papillae or villi, and 
between them are seen the honey-comb depressions which were 
described by Sir E. Home.* When we examine an oblique or 
perpendicular cut of the membrane under a simple microscope, 
we observe thousands of these villi projecting up from the sur- 
face of the membrane, like the pile of velvet, so as to form a 
sort of fleece. The honey-comb depression between these villi, 
according to the observations of Dr. Boehm,f and Dr. Sprott 
Boyd,{ are composed of many tubular follicles, placed perpen- 
dicularly in the membrane, and which open into the surface of 
the cell. The diameter of these cells, according to Dr. Boyd, 
varied from the T £oth to the T ^th part of an inch. The bases of 
these follicles rest upon the cellular coat of the stomach, and are 
considered by Dr. Boehm, as similar to the tubular follicles of the 
large intestines. (See Fig. 47, page 69.) 

— The villi or papillae of the mucous membranes are much more 
fully developed in the small intestines than in any other part of the 
alimentary canal, with the exception of those upon the tongue. 
They were first discovered by Fallopius. They occupy the whole 
length of the small intestines; studding the valvulae conniven- 

* Sir E. Home described these honey-comb depressions as existing only in the 
left extremity of the stomach, and considered the remaining portion of the stomach 
occupied by the villi. Careful inspection, as Cruveilhier has observed, will show, 
that the whole surface of the membrane is constructed alike in this respect, with 
the exception, that the nipple-like or mammelonnated projections, are more fully 
developed on the side of the pylorus, than at the cardiac extremity of the stomach. 
A good idea of the appearance of the villi of the stomach when examined by the 
microscope, may be formed from an inspection of the papillae villossB of the tongue, 
between the bases of whicli we are to consider placed the honey-comb depressions. 

Ruysh has divided the villous prominences of the gastric mucous membrane 
into two classes, papilla and villi, in which he has been followed by some anato- 
mists : hence the gastric mucous membrane has been called the villoso-papillary. 
But this distinction does not appear to be well founded. Careful observation with 
the microscope, does not enable us to perceive any difference between them, and 
they may be called indifferently, villi or papilla?, and considered as the representa- 
tives in the mucous membranes of the papillae of the skin. — p. 

t De Gland. Intes. Struct. Penit. Berol, 1835.— p. 

J Essay on the structure of the mucous membrane of the stomach. Edinburgh, 
1836.— p. 

6* 



66 VESSELS AND NERVES OF MUCOUS MEMBRANES. 

tes, as well as the spaces between them. Their number is very 
considerable: Lieberkiihn estimated them at 500,000. Some 
of the German anatomists, have more recently made a higher 
estimate of their number than this. They assert that there are 
4000 to be seen upon every square inch of surface, and which 
by their calculation would make a million of villi to the small 
intestines. 

— Those of the jejunum, according to the measurements of Dr. 
Homer, are the thirtieth of an inch in length, and those of the 
ileum the sixtieth. In the pyloric half of the stomach and in the 
duodenum, according to Beclard, they are formed of a fold of 
the mucous membrane, the transverse diameter of which exceeds 
the length, and which has a tufted arangement. In the jejunum 
they consist of longer folds, forming semi-oval plates touching 
one another at their basis. In the ileum, according to Dr. Horner, 
they form slightly conical projections. 

— The villi can be studied to the best advantage after a minute 
injection of the vessels of the mucous membranes, which by 
rendering the vessels of the villi turgid, throws them into a state 
of erection, like that which takes place in the papillae of the skin 
when they are in a state of functional activity. The peculiar 
developement of the villi of the small intestines which will be 
subsequently considered,* is attended probably by a peculiarity of 
organization, apparently for the purpose of fitting them for a 
function which they alone possess ; that of chylous absorption. 
— In the other mucous membranes, the presence of the villi are 
by no means so obvious, though they may be detected by the 
microscope. 

The Vessels and Nerves of Mucous Membranes. 
— In the submucous cellular or nervous tissue, are found the 
larger branches of the arteries, veins, and nerves, whose final 
ramifications take place in the mucous membranes and their 
villous productions. The vessels are derived from contiguous 
trunks. The veins arc far more numerous than the arteries, and 
seem to exceed here the large proportion which they bear to the 

* See General Anatomy of Absorbent System.— r. 



ABSORBENT VESSELS. qj 

veins in other portions of the body. They form, as shown by 
the elegant preparations of Professor Horner, a plexus on the 
surface of the membrane, which overlays the arteries, and in 
which, when successfully injected, a straggling arterial branch is 
only here and there visible. Beneath this plexus, however, and 
mixed up with larger veins which anastomose with the superficial 
venous plexus, the arteries ramify to a great degree of minuteness. 

Of the Absorbent Vessels. 

— The lacteals of the small intestines arise partly from the villi, 
and partly from the surface of the intervillous mucous membrane. 
Nearly all the best recent microscopical observers now agree, 
that there are no orifices of the lacteals visible in the villi of the 
intestines. The villi are short processes, a quarter of a line, or 
at most a line and two-thirds in length, which project above the 
surface of the mucous membrane and give it, when magnified, 
the appearance of a thick fleece. Their form is various, cylin- 
drical, pyramidal or lamellated. In most of our domestic animals, 
they are generally flattened, broad at the base, which runs off 
into a fold of the mucous membrane, so that many of the villi 
appear only as a modification of the rugse or folds of the mem- 
brane. The villi are formed exteriorly by a coating of mucous 
membrane, filled within by a net-work of minute blood-vessels, 
which can only be well demonstrated by injection, and in which 
the lacteals take their origin by branches anastomosing in the 
form of net-work. Fig. 45, is a magnified 
representation of a villus, seen by Krause, of *'S" 45, 

Hanover, in the jejunum of a young man, 
who had been executed shortly after eating, 
and in which the lacteals were filled with 
chyle. The mucous membrane between the 
villi, when examined with a single micro- 
scope, presents an extraordinary number of 
small orifices, which are the openings of Lie- 
berkiihn's follicles. See Figs. 47 and 50. 
— Fohman, in his most perfect mercurial injection of the lacteals 




68 OF THE NERVES AND MUCOU3 FOLLtCLES. 

of the intestine in fishes, and Schwann, in the injection of the 
lacteals in the intestinal villi in man, found no mercury what- 
ever to escape into the cavity of the intestine. Hence it may 
be inferred, either that there are no open orifices by which 
they communicate with the cavity of the intestine, or that they 
are so exceedingly minute, that no one has yet been able to dis- 
cover them with the microscope. The origin of the lacteals in 
the villi, is, in all probability, the same as that of absorbents in 
other parts of the body, by a net-work of extreme minuteness.* 
— Fig. 46, is a representation of the „. „ , 

origin of the absorbents from the mucous 
membrane of the stomach, in the form 
of a net- work, as they appeared to 
Breschet. 

— The very presence of the intestinal 
villi, found in man and the superior ani- 
mals, is not indispensable to chylous 
absorption, for, in a large number of 
animals, the internal surface of the small intestines is destitute 
of villi. 

Of the Nerves. 

— The nerves of these membranes, are derived in many parts, 
as the intestines, biliary ducts, etc., mainly from the sympathetic 
nervous system ; hence such parts are necessarily devoid of ani- 
mal sensibility. In the stomach, upper part of duodenum, oeso- 
phagus, mouth, lungs, and rectum, it receives branches likewise 
from the cerebro-spinal system, which places it in those parts, 
partly in the dominion of the animal functions. 

Of the Blennogenous or Muciferous Glands. 

— These exist in great numbers in all mucous membranes, and 
are the source of the mucous substance, which covers the sur- 
face of the membrane. 

* This is a doctrine long since advocated by Hewson. — p. 

+ a, A layer of superficial absorbents. 6, A layer more deep sealed. p, 




LIEBEUKUHN'S FOLLICLES. 69 

—The anatomy of these organs, has heretofore been involved 
in a considerable degree of confusion, and though it is not yet 
satisfactorily established, enough has been done to enable us to 
make a division of them into classes, so as to render the descrip- 
tion of them more intelligible. 

— From the researches of recent observers, they may be divided 
into two classes. The first, comprising the mucous follicles or 
mucous cryptae, and mucous glands. The second class is com- 
posed of some vesicular bodies, which may be subdivided into, 
1st, The glandulae solitarise, (glands of Brunner, of some anato- 
mists,) and 2d, The so called glandulae agminatse, or glands of 
Peyer. The two first are generally spread throughout the mu- 
cous membranes, and seem to differ from each other but little, 
except in regard to the degree of their developement. The 
mucous follicles are entirely microscopical ; and were first 
particularly described by Lieberkiihn in the small intestines, 
where they are frequently called the follicles of Lieberkiihn. 
— If a portion of the mucous membrane of a small intestine be 
well washed, we may readily discover, by means of a simple 
microscope, around the basis of the villi an extraordinary num- 
ber of orifices not visible to the naked eye, which are the open- 
ing of Lieberkiihn's follicles ; these openings are about eight or 
ten times as large in diameter, as the red particles of the blood.* 
Sometimes these openings are so close and numerous, that the 
space between the orifices is scarcely so broad as the orifices 
themselves; generally, however, they are more widely sepa- 
rated, in which case they give a spongy appearance to the mem- 
brane. These follicles of the small intestines, which were observed 
by Lieberkiihn, appears to be the exact coun- 
terpart of the tubular follicles observed in the 
whole extent of the mucous membrane of the 
large intestine by Dr. Boehm, and in the 
mucous membrane of the stomach by Dr. 
Boyd. C, Is an enlarged view of the tubular 
follicles of the large intestine, as they appear- 

• Mailer's Physiology, p. 260.— p. 




70 NUMBER OF FOLLICLES. 

ed to Dr. Boehm. D, Is the natural size of the piece magnified. 
They are arranged side by side perpendicularly in the membrane, 
their closed or caecal bases resting upon the subjacent cellular 
tunic of the intestines, as seen at 2, which represents a per- 
pendicular cut through the mucous membrane, down to the cel- 
lular coat. 3, Is the surface of the cellular coat, from which the 
mucous membrane has been removed, showing the pits or de- 
pressions in which the basis of the follicles are lodged. 1, Is 
the free surface of the mucous membrane, showing the openings 
of the follicles which are believed to be the same as the orifices 
of Lieberkiihn. 

— In the stomach, the cryptas alone are said to exist, except at the 
curvatures, where a few of Brunner's glands are met with ; yet 
in a child dead from summer cholera, the follicles were so en- 
larged or hypertrophied that I could distinctly count with the 
naked eye, in a square inch on the sides of the stomach near 
the pylorus, a hundred and twenty-five opaque bodies below the 
membrane, which presented all the usual characteristics of the 
glands of Brunner in the small intestines. In the same subject, 
the glands of Brunner,* {duodenal and mucous glands,) were 
much enlarged ; and in the same extent of surface, I counted 
without a glass, a hundred and seventeen in the duodenum, 
ninety-five in the upper portion of the jejunum, and thirty-five at 
the commencement of the ileum. 

— Dr. Horner,f who is justly distinguished as an anatomical dis- 
coverer, has made, with the assistance of Dr. Goddard, the size 
and number of these follicles, the subject of attentive microsco- 
pical examination. He has found them to vary in size in the 
stomach from the -gVth to the 4-bth part of an inch in diameter, 
and in the colon from the 275th to the T £ ff th. He estimates the 
whole number of follicles in the stomach and intestines, at forty- 
six millions, nine hundred thousand, and upwards. Of these there 
belong to the stomach, one million, two hundred and ninety-six 
thousand ; to the small intestines, thirty-six millions, and to the 
colon, nine millions, six hundred and twenty thousand. And to 

* De Structura Glandulorum Intestinorum. Berl. 1836. — p. 
t Special and General Anatomy, vol. 2, p. 40, fourth edition. p. 



MUCOUS GLANDS. 7 J 

the inch square, in the stomach, fourteen thousand, four hundred, 
in the small intestines, ticenty-five thousand, and in the colon, 
nineteen thousand, two hundred,* 

— The mucous glands, compared with the follicles or cryptae, are 
generally of considerable size, and visible to the naked eye ; and 
in fact appear only to be compound cryptae. They are little 
bodies placed in the submucous cellular tissue, appearing slight- 
ly lobulated when examined with the microscope, and containing 
minute cells, lined by a reflection of the mucous membrane. 
These are found most abundant in parts of the mucous mem- 
brane, where, from its exposure to acrid or irritating substances, 
the membrane would appear to need the most protection from 
the mucous coating ; as in the mouth, the duodenum and the 
rectum. 

— These glands have already been described in the trachea and 
bronchia, etc. They bear names in many places according to 
their location, as labial, buccal, palatal, oesophageal, and duo- 
denal. In the duodenum, of all places, they are most abundant 
where the acrid and irritating biliary secretion first comes in 
contact with the mucous membrane of the alimentary canal. 
To these only properly belong the term of glands of Brunner, 
for to these his description was mainly applied. 
— Brunner was the first to describe in the mucous membrane of 
the duodenum, a series of flattened glandular granulations, stud- 
ding thickly the upper half or two-thirds of this membrane, and 
which he considered analogous in structure to the granular acini 
of the pancreas. 

— He considered them also similar in structure to the solitary 
glands; but in this respect he has been proved to be in error. 
Cruveilhier has observed the analogy of these glands, not only 
with the acini of the pancreas, but with those of the different 
salivary glands. These glands he found to diminish gradually 
in number, towards the lower end of the duodenum, so that none 
was to be observed farther down than the commencement of the 
jejunum. Dr. Boehm has verified these observations of Cruveil- 
hier, and shown that they are little solid glands, formed of several 

* Lalut has estimated the follicles of the small intestines at 40,000. — p. 



72 



GL.ANDUL.iE SOLITARIjE. 



minute lobules, each of which is found to be cellular; and that 
all the cells of each gland open by a common orifice. 
—The third and fourth order of glands, the glandules solitaries, 
and the glandules agminatcs, are met with only in the alimentary 
canal. The latter are found almost entirely in the lower half of 
the small intestines, and it has been rendered questionable by the 
researches of Boehrn and Miiller, whether solitary glands of the 
small intestines do not differ from those met with in the stomach 
and large intestines. 

—The solitary glands are found at the end of the small intestine, 
in the large intestine, and a few along the lesser curvature of the 
stomach. They present the appearance of small granulations of 
the size of millet seed, and which project slightly on the internal 
surface of the mucous membrane. Neither Boehrn, nor Miiller, 
who has verified all Boehm's researches by his own use of the 
microscope, have been able to discover in the undiseased state, 
Fig. 48. any opening of the solitary glands of the small 

intestine. But when ulcerated in tubercular 
affections, or in dothinenteritis, the cavity 
is exposed. Fig. 48, is a magnified repre- 
sentation of one of the solitary follicles or 
sacculi of the small intestines after Boehrn. 
It has no apparent orifice ; it is studded with 
villi, and round it are seen the orifices of Lieberkuhn's follicles. 
— In the large intestines, the orifices of these follicles are readily 
„. .„ discovered. B, is a repre- 

sentation of one of the soli- 
tary follicles of the large in- 
testine, by the same author, in 
which the orifice may be dis- 
covered in the centre, with 
many of the openings of Lieberkuhn's follicles around it. A, is a 
vertical section of the same follicle, showing its cavity and the 
orifice by which it communicates with the interior of the large 
intestine. Around it are seen the vertical tubular follicles of 
Boehrn, which appear to be synonymous with the follicles of 
Lieberkuhn. 





GLANDS OF PEYER. 73 

The Glandules AgminatcB, 

— Are better known under the name of glands of Peyer, after a 
young anatomist who described them, as well as the solitary 
glands with much minuteness,* though they had previously been 
pointed out by Pechlin, under the name of Vesicularum Agmina. 
— These so called agminated follicles, present themselves as 
patches under a variety of forms, generally elliptical, but some- 
times circular or oblong. The longest diameter of the patches 
when they are either elliptical or oblong, is always parallel with 
the axis of the intestines. The patches are met with of all sizes 
from two or three inches in their longest diameter, to a few 
lines only. They vary also in regard to number; sometimes 
fifteen or twenty only, are met with in one subject, and some- 
times thirty or more. 

— In all cases they are found placed in the mucous membrane, 
on the side over against the insertion of the mesentery. They 
are found only in the small intestines, and usually in the lower 
half, and are most numerous near the termination of the small in- 
testines in the colon. Peyer, however, asserts, that he discovered 
in one instance a patch in the duodenum. These patches appear 
to be formed of an agglomeration of entirely distinct bodies, 
exactly analogous to the solitary glands of the small intestines; 
and in some cases where the number or size of these agminated 
glands of Peyer is less than usual, the number of the solitary 
glands in the same region of intestine, appears to be increased. 
— The appearance which these glands of Peyer present, is, how- 
ever, in other respects very variable. Sometimes in perfectly 
healthy intestines, they can scarcely if at all be distinguished ; 
and when seen, generally appear, if held up between the observer 
and the light, as little vesicles like those in the rind of an 
orange, and in which no orifice can be seen even with the glass. 
In tubercular disease, and especially in typhoid fever with affec- 
tion of the bowels, (dothinenteritis,) they are usually found en- 
larged, and ulcerated so as to expose an abrupt cellular cavity. 

* De Glandulis Intestinorum. J. Conradus Peyer, 1667. — p. 
VOL. II. 7 



74 



GENERAL ANATOMY OF THE MUCOUS TISSUE. 



The structure of these solitary and agminated glands, so different 
from that of the other follicles of mucous membranes, has lately 
attracted considerable attention, and the researches of Boehm* 
and Mullerf have rendered it doubtful, whether they really be- 
long to the class of follicles or not. 

— Fig. 50, is part of a patch of Peyer's glands greatly magni- 
fied, (after Boehm.) Here the follicles of Peyer are seen as cir- 
cular white spots, about a line in diameter, with no apparent 
orifice, and surrounded with a circular zone of foramina, which 
belong, as well as those scattered between the glands, to Lieber- 
kuhn's follicles. Dr. Boehm tried in vain to express any secretion 
from the white bodies through an external opening, as he proba- 
bly could have done, had they been follicles; nor was he more 
successful in endeavouring to force it through the orifices form- 
ing the zone. On rupturing 

one of the bodies, a cavity Fig. 50. 

was opened similar in extent 
to the white body itself, in 
which was found a grayish 
white mucous matter, com- 
posed of particles smaller 
than the ordinary particles 
of mucus. According then 
to Boehm and Miiller, there 
are not, in the healthy state, 
in the patches of the so call- 
ed Pey e r's gl a nd s, a ny 1 a rge ISJ' \ 
follicles with open mouth or 
cells, but merely sacculi, of which the nature is unknown. 
—Fig. 48, p. 72, is a representation after Boehm, of one of the 
solitary glands of the small intestines, which have been con- 
founded with the glands of Brunner, and which is precisely simi- 
lar in structure and appearance, to one of the bodies in the 
patches of Peyer, with the exception that its surface is 
thickly studded with villi. 

* Loc. cit. — p. 

t De Glandularis Secernent. Structura penitiora, etc. Leipsic, 1830.— p. 




more 



GENERAL ANATOMY OF THE GLANDULAR SYSTEM. 75 

General Anatomy of the Glandular Tissue. 

Any original structure that discharges from the blood-vessels 
a fluid different from those which they naturally contain, may 
be considered as glandular. The function or process by which 
such fluids are derived from the blood-vessels is called secretion. 

A structure of this kind seems to exist in very different situa- 
tions: for it is distinctly circumscribed in many of those bodies 
commonly denominated glands, which are of a very precise 
form ; and it is also diffused on some very extensive surfaces. 
The gastric liquor, a most important secretion, is probably dis- 
charged from vessels which open, like exhalents, on the internal 
surface of the stomach, and not from any circumscribed bodies, 
which are generally denominated Glands. 

The name of gland is theoretically applied to several bodies 
which cannot be proved to secrete any fluid whatever; and also 
to those bodies connected with the absorbent vessels, which are 
called the Lymphatic Glands; but it is most commonly appro- 
priated to those organs which discharge a fluid different from 
the blood. 

The structure by which mucus is secreted in some places, 
appears to be very simple. Thus, in the Schneiderian membrane 
and the urethra, there are small ducts from four to six lines in 
length, and equal in diameter to a bristle, which appear to be 
formed of the membrane on which they open. From these ducts 
mucus issues to cover the surface of these membranes. In many 
instances there is no substance resembling that of the circum- 
scribed glandular bodies, connected with these ducts ; but the 
secreted fluid seems to be discharged into the ducts from the 
small vessels on their surfaces. The ducts of this nature in the 
urethra are denominated Lacuna. 

In some other parts of the body, the cavities into which mucus 
is discharged are somewhat different, both in form and size, from 
those above mentioned, and are called Follicles. These cavities 
are surrounded with more or less of a pulpy vascular substance, 
which has been considered as glandular, and essential to the 
mucous secretion. 



70 GENERAL ANATOMY OF THE 

The circumscribed bodies, which are commonly called glands, 
differ in their internal appearance and texture, from the other 
parts of animals. The substance of which they consist differs 
very much in the different glands; and thus renders the liver, 
kidneys, salivary glands, mammas, &c, very different from each 
other. Some glands, as the salivary, &c, are composed of 
several series of lobuli that successively diminish. The smallest 
of these are denominated Acini. Each of them is connected by 
a small artery and vein, to the large blood-vessels of the glands ; 
and also sends a branch to join the excretory duct. 

These Acini are therefore connected to each other, by the 
blood-vessels and excretory duct of the gland, and also by the 
cellular membrane which covers them externally, and occasions 
them to adhere to each other where they are in contact. In 
consequence of this structure, these glands have a granulated 
appearance. 

The liver, when incised with a sharp instrument, appears dif- 
ferently; but when broken into pieces, it seems to consist of 
small acini. Some other glands, as the Prostate, appear to be 
uniform in their texture, and have none of this granulated ap- 
pearance. 

The structure of glands has long been an interesting object of 
anatomical inquiry, and was investigated with great assiduity by 
those eminent anatomists, Malpighi and Ruysch. 

Malpighi, as was formerly observed, used ink and other co- 
loured fluids in his injections. He was also very skilful in the 
use of microscopes, and took great pains in macerating and 
preparing the subjects of his inquiries. Ruysch, on the other 
hand, used a ceraceous injection, and was most eminently suc- 
cessful in filling very small vessels with it. Malpighi believed 
that there were follicles or cavities in glandular bodies, which 
existed between the extremities of the arteries and the com- 
mencement of the excretory ducts of those bodies, and that in 
these cavities the secreted fluids underwent a change.— Ruysch 
contended, that the arteries of glands were continued into ex- 
cretory ducts, without the intervention of any cavity or follicle; 
that the small bodies which had been supposed to contain follicles 



GLANDULAR SYSTEM. 77 

or crypts, were formed by convolutions of vessels, and that the 
change of the fluid, or the process of secretion, is produced by 
the minute ramifications of the artery. 

A very interesting account of this subject is contained in two 
celebrated letters, which passed between Boerhaave and Ruysch 
in the year 1721, and are published at the end of the fourth vo- 
lume of the works of Ruysch. 

The opinion of Ruysch has been more generally adopted by 
anatomists, and has derived support and confirmation from se- 
veral anatomists since his time. The late Mr. Hewson declared 
his conviction that the small globular bodies which are scattered 
through the kidneys, and were supposed to be follicles or cryptae, 
are merely convoluted arteries. He also asserted, that the acini 
which appeared in the mammce as large as the heads of pins, 
when the excretory ducts of that gland were injected with ver- 
milion and painters' size, proved to be the minute ramifications 
of the excretory duct, which divided very suddenly into branches 
so small that they could not readily be seen by the naked eye.* 

Notwithstanding these reasons for supposing that the excretory 
ducts of glands were derived simply from the arteries of those 
bodies, it is said that the late Dr. W. Hunter used to declare his 
belief, that there was a part in glands which was not injected in 
his preparations; and to say farther, that he believed his prepara- 
tions were injected as minutely as those of Ruysch. 

All of these opinions have been strenuously controverted by 
the Italian anatomist, Mascagni, who believes that the arteries 
terminate only in veins; and of course that they neither form 
exhalent vessels, nor communicate with the excretory ducts of 
glands. His idea of the structure of glands is different from 
those either of Malpighi or of Ruysch. 

He supposes that glands contain a great number of minute 
cells ; that the arteries, veins, and absorbent vessels are spread 
upon the surfaces of these cells, in great numbers, and very irre- 
gularly. From these celis very small canals originate, which 
unite to form the small branches of the excretory ducts. Ac- 
See Experimental Inquiries, vol. ii. p. 178. 

7 * 



•78 GENERAL ANATOMY OF 

cording to his idea, the secreted fluid is discharged through 
pores or orifices of the blood-vessels, into the cells, and proceeds 
from them through the canals, into the branches of the excretory 
ducts. Absorbent vessels, in great numbers, originate from 
these cells. 

In his great work on the absorbent system, when treating on 
the termination of arteries and the commencement of veins, 
(Part I, Section 2,) he asserts, that if the kidneys are successfully 
injected with size, coloured with vermilion, and then laid open 
by a section of a razor, it will be found that the size without the 
colour has passed into cells which are very numerous; that the 
arteries and veins are ramified most minutely on the surfaces of 
these cells, and that the tubuli uriniferi, as well as the absorbent 
vessels, originate from them. 

He supposes that a considerable portion of the fluid thus passing 
off from the blood-vessels, is commonly taken up by the absorbent 
vessels of the kidneys : for in two cases in which he found the 
absorbent vessels obstructed, a diabetis existed, which he con- 
sidered as the effect of the inactivity of the absorbents. He 
asserts, that in the liver, pancreas, mammas, and also in the sa- 
livary and lachrymal glands, the minute arteries and veins are 
also distributed upon the surfaces of cells ; and that very small 
canals arise from these cells, and unite to form the small branches 
of the excretory ducts. 

This great anatomist appears to have been much occupied 
with microscopical observations, and has gone largely into the 
discussion of this subject.* 

— The opinions of the distinguished anatomists which have 
been detailed above, conflict, as has been seen, considerably with 
each other. They were, however, legitimate deductions from 
their own experiments and observations, and each entitled to 
credit, since every one of these great men has added con- 
siderably to the knowledge of this interesting and intricate 

* The late Dr. W. Hunter, in his Medical Commentaries, (p. 40,) avowed his 
belief, that the fluids which appear occasionally in the various cavities of the body, 
transude through the coats of the blood-vessels. Mr. Hcwson, (Experimental In- 
quiries, Vol. II. Chap. .7,) suggested several reasons for dissenting from this opision; 
but Mascagni has endeavoured to support it— See a long note to the above men- 
tioned section of this work, page 74. 



THE GLANDULAR SYSTEM. 



79 



department of general anatomy. Since then, other observers 
have contributed much to the elucidation of the structure of dif- 
ferent glands, of whom we shall hereafter have occasion to speak ; 
and lastly, Muller has published a work, ex professo,* upon the 
subject, which has reconciled many of these conflicting opinions. 
This observer has extended his investigation into the comparative 
anatomy of all the glands, and to their developement at the 
different stages of foetal life, and having a full acquaintance 
with all that had been previously discovered, his researches 
may be looked upon as classical upon this subject. 
— Of all the various opinions entertained, that of Malpighi ac- 
cording to Muller, was nearest the truth; viz., that the elementary 
parts of all glands, the so named acini or granules, have the same 
structure as the simple and compound follicles or follicular 
glands, each one consisting of minute, roundish sacs, which 
receives its secretion from the blood-vessels distributed on its 
walls, and which secretion is poured into the efferent duct. 
But these cavities, which Malpighi believed to be single element- 
ary follicles, and Mascagni and Cruikshank simple cells, have 
been shown by Muller, to consist of an aggregate of many mi- 
nute ramifications of the duct, which terminate by closed or 
cascal pouches, as is seen in Fig. 51, upon which the vessels 
ramify, and which constitute the real elementary parts of the 
gland. 

— The individual forms, which these minute 
ramifications of the secretory ducts assume, 
vary, however, somewhat in the different 
glands, though they are alike in the general 
result; that of forming an independent sys- 
tem of tubes, ramifying so as to gain a great 
extent of surface for their lining membrane. 
The finest secreting tubes, which are closed 
at their extremities like the follicles of the °** 
simple mucous membranes, are never, how- 

* De Glandularum Seccrnentium Structura Penitiore, earumque prima forma- 
tione, etc. Leips. 1830. — p. 

t This is a magnified representation after Weber, of a portion of a parotid 
gland. The smaller figure is the natural size of the piece magnified, a, The 
cells clustered on the extreme branches of the duct of Steno. — p. 



Fig. 51.f 




80 



GENERAL ANATOMY OF THE GLANDULAR SYSTEM. 



ever, as has been proved by microscopical measurement, so mi- 
nute as the compound follicle, in which there is a single duct com- 
mon to several exceedingly minute follicles of the simple kind; 
which seem to be formed by the amplification of the surface of 
a simple follicle, depressed on its sides into a number of cellular 
dilatations which open through the common duct. Specimens of 
these, are to be found in the Meibomian glands, the tonsil, labial, 
buccal, duodenal glands, etc. 

— In other more complicated glands, is found a further develope- 
ment of the follicular sac, and the excretory tube. In these com- 
pound or conglomerate glands, such as the lachrymal, mammary, 
salivary glands, pancreas, liver, etc., the excretory tube is longer 
and ramifies in the manner of a tree. In some, the tubes ramify 
with a certain degree of regularity, as in the mammary gland, 
represented in the following figure. 

Fig. 52.* 




— The divisions given off by the main duct of the gland divide 
again by giving off side branches; these divide and subdivide in 
like manner in their turn, till finally, a subordinate branch of 
minute size terminates in a cluster of blind pouches or follicles, 
which are invested on their outer face by cellular tissue, and capil- 
lary vessels, and form one of the acini or granules of a gland. A 

* The diameter of the cells or terminal cavities of the lactiferous ducts, is large, 
compared with those of many other glands; it is from ten to thirty-five times 
greater, according to Mailer, than that of the smallest capillary vessels in the 
human body. — p. 



CAPILLARY BLOOD-VESSELS OF THE GLANDS. gj 

collection of these acini, which correspond to a particular division 
of the excretory duct, will necessarily be a little separated from 
other pans of the gland, and is called a lobule. This is the ar- 
rangement in all the lobulated glands, viz. the lachrymal, mam- 
mary, salivary glands, and the pancreas. Each acinus is not 
therefore, as was supposed by Malpighi, Ruysch, and Mascagni, 
a single cell, but a cluster of cells, too minute to be seen, except 
in the distended state and by the aid of the microscope, seated 
upon the extremity of a minute branch of the excretory tube, 
and surrounded by a net-work of capillaries, exactly analogous 
in structure to one of the mucous glands of the mouth, or of the 
duodenum. Sometimes, instead of the short cells of the acini, 
the ducts terminate in long excretory tubes, as in the kidney and 
testis, when the length of the tube compensates in regard to the 
extent of secretory surface, for the nondivision into cells. 
— In some glands, as in the liver of man and all the vertebrate 
animals, and in the kidneys of oviparous animals, where there is 
a portal circulation, and the secretion is made from venous blood, 
the arrangement is somewhat peculiar. The ducts ramify 
irregularly, present no arborescent arrangement, and there is no 
distinct division into separate lobules. The excretory ducts ter- 
minate in the acini, in the form of tufts of microscopical tubes, 
which anastomose together so as to form a sort of net-work in the 
body of the acinus : the centre of each acinus, in these peculiarly 
constructed glands, being occupied by a vein, according to Kier- 
nan,* which carries away the blood of the portal system, after its 
excrementitious parts have, by the secretory action, been trans- 
ferred to the branches of the excretory duct. 

Capillary Blood- Vessels. 
— Those of the liver and kidneys are considered the most minute ; 
yet these have a diameter two or three times as large as the 
minute arteries and veins, which may be seen with the micro- 
scope, ramifying on the ducts and forming a capillary net-work 
on their walls and interstices, and from which the fluids are dis- 
tilled into the cavities of the tubes, modified in different parts, so 
as to constitute the peculiar secretions. Thus, in the kidney and 

* See Anatomy of Liver. — p. 



82 MICROSCOPICAL MEASUREMENTS. 

testis, the ducts are arranged in convolutions and terminate ab- 
rur tly in a cul de sac; in the pancreas, salivary and mammary 
glands, etc. they have an arborescent arrangement, and terminate 
in grape-like clusters of cells ; the general fact of the distribution 
of these vessels upon their wails, and the mode in which secre- 
tion is effected being much the same in all. There is no inoscula- 
tion or direct termination of a blood-vessel in a duct as Ruysch 
supposed, and the experiments that have given rise to this 
opinion, that of passing a fluid by forcible injection from a secre- 
tory duct into a blood-vessel, or vice versa, have been attended 
by a rupture of the fragile structure of the glands, by which the 
injection has mechanically insinuated itself from one system of 
vessels into the other. 

— The simplest form of gland, is that of a mere depression or 
recess in the surface of a membrane, as the sebaceous follicles of 
the skin or cryptse or follicles of the mucous membrane. These 
have but a simple orifice, or a short duct. The next degree, of 
complication in the structure of glands, is that of the cellulated 
or compound follicle, and its highest degree of developement is 
met with in the conglomerate glands, as the parotid, the mam- 
mary, and the liver. 

Microscopical Measurement of the Diameter of the Capillary 
Vessels, and Ultimate Divisions of the Excretory Tubes in 
some of the Glands. 

Parts of an Inch. 

Capillary blood-vessels, according to Weber, ^^ to y-^ 

in the kidneys, " Muller, ^l._ to TI Vo 

The smallest pulmonary air-cells in the human sub- 
ject (Weber,) which have a termination some- 
what like the ducts of glands, - - _^_ to A 
Tubuli uriniferi in the cortical substance of the 
human kidney, (Weber,) 

" " in the pyramidal portion, 

" " in the papilla?, 

Tubuli seminiferi of man, (Muller,) 

" " distended with mercury, 

Tubuli recti testis, (Lauth,) (undistended,) 
Cells of the Meibomian glands, (Weber,) - -L to " 



_i_ 

5 1 2 

i_ 

923 

1 

TTT 

1 

97 

1 

99 



ACTION OF GLANDS. 



83 



It must, however, be acknowledged, that no information which has as yet 
been obtained respecting the structure of glands, enables us to explain 
their wonderful effect upon the fluids which pass through them. Jt re- 
mains yet to be ascertained why one structure forms saliva and another 
bile ; or why so much apparatus should be necessary for the secretion of 
milk when adipose matter appears to be produced by the mere membrane 
in which it is contained. 

Dr. Berzelius, professor of Chemistry at Stockholm, in a late work on animal 
chemistry, asserts, that if all the nerves going to a secretory organ are 
divided, secretion will cease, notwithstanding the continued circulation of 
the blood. From this, he thinks, that secretions depend upon the influence 
of nerves, although he cannot explain their effects. 

Mr. Home, after relating some experiments upon blood and serum, made 
with the Voltaic Battery, proposes the following questions, among others : 
Whether a weaker power of electricity than any which can be kept up 
by art, may be capable of separating from the blood the different parts of 
which it is composed ; and forming new combinations of the parts so se- 
parated'! Whether the structure of the nerves may enable them to pos- 
sess a low electrical power, which can be employed for that purpose 1 &c. 
See the London Philosophical Transactions, for 1809, part II.* 

* Mr. Wollaston has also published a small paper on this subject, in the Philo- 
sophical Magazine, vol. 33. 



Q4 OF THE LIVEB. 



CHAPTER III. 

OF THE LIVER, THE PANCREAS, AND THE SPLEEN. 

Of the Liver. 

This largest viscus of the abdomen, when in a healthy con- 
dition, is of a reddish brown colour. If it is taken out of the 
subject, and laid on a flat surface, it is flat, but in the abdomen it 
is convex and concave. 

It is situated in the right hypochondriac region, which it oc- 
cupies entirely; and extends through the upper portion of the 
epigastric into the left hypochondriac region. Being placed 
immediately under the diaphragm, and in close contact with it, 
as well as with the inner surface of the right hypochondriac 
region, it partakes of their form, and is convex above and con- 
cave below. When thus situated, it is of an irregular figure, 
between the circular and the oval, but is broader at the right 
extremity than at the left, and very irregular in thickness. The 
edge or margin which is in contact with the posterior part of the 
right hypochondriac region, is very thick. It gradually becomes 
thinner towards the left, and also towards the front ; so that the 
right margin, and a large portion of the posterior margin, is very 
thick, while the left and anterior margin is thin. 

The upper convex surface of the liver, when in its natural 
situation is smooth : the lower concave surface is marked by 
several grooves or fissures and eminences. One of these, called 
the Umbilical or the great fissure, commences at a notch in the 
anterior edge of the liver, to the left of the middle, and continues 
to the posterior edge. At the commencement of this fissure the 
umbilical ligament enters; and at the termination, or near it, the 
vena cava is situated. Opposite to this fissure, on the upper or 
convex surface, is a ligament passing from the diaphragm to the 



LOBES AND FISSURES OF THE LIVER. 



85 



liver, which is called the falciform. The fissure and the ligament 
divide the liver into its two great lobes, the Right and Left. 

Another great fissure, called the transverse or principal, com- 
mences on the right lobe and extends to the left, crossing the 
first mentioned fissure at right angles, and extending a very short 
distance beyond it. It is very deep and rather nearer to the 
posterior than the anterior edge of the liver. In this fissure, 
near to its right extremity, the great vein, called vena portarum, 
and the hepatic artery enter, and the excretory duct of the liver, 
commonly called the hepatic duct, comes out. About the middle 
of the fissure are two prominences, one on each side; these 
were called the porta?, or gates of the liver, and hence the great 
vein was called vena portarum. This vein has two very large 
rectangular branches, which constitute what is called the sinus of 
the vena portarum ; and they occupy the principal extent of the 
fissure. 

The liver is in close contact with the vena cava behind ; and 
there is either a groove in it for the passage of the vein, or this 
great vessel is completely enclosed by it. There is also an ex- 
cavation on the lower surface of the liver, which is occupied by 
a portion of the gall-bladder. 

Besides the great lobes above mentioned, there are also two or 
three prominent parts, in the concave surface, which are deno- 
minated lobes. One of these, called Lobulus Spigelii, is oblong, 
with two sides, and an angle continued along its whole length, 
which extends from the transverse fissure on the posterior mar- 
gin of the liver. It is situated between the posterior part of the 
transverse fissure, or ductus venosus, and the vena cava. 

The anterior extremity of this lobe, which forms one of the 
margins of the transverse fissure, is somewhat bifurcated, and 
has been called lobulus caudatus. The largest portion of the 
bifurcated end forms a process like a papilla, and is one of the 
porta?. 

Between the umbilical fissure and the depression for the gall- 
bladder is a protuberant space, which varies from an inch and a 
quarter to two inches in breadth. This has also been called a 
lobe, Lobulus Quartus or Anonymous ; its posterior point, oppo- 

VOL. II. 8 



g(J UGAMENTS OF THE LIVER. 

site the papilla of the lobulus spigelii forms the other part of the 
liver. 

The peritoneum is extended from the surface of the abdomen 
to the surface of the liver, in such manner as to cover it, and to 
form ligaments, which have a great effect in retaining it in its 
proper situation. The whole posterior edge of the liver is in 
contact with the back of the abdomen. The peritoneum above 
the liver is reflected to the upper surface of it, and the perito- 
neum below it to the lower surface; so that two lamina of the 
peritoneum pass from the lower part of the diaphragm at the 
back of the abdomen to the posterior edge of the liver. These 
processes of the peritoneum are considered as forming two liga- 
ments, which are called the right and left lateral ligaments. A 
portion of the posterior surface of the liver, uncovered by the 
peritoneum, is often in contact with a portion of the tendon of 
the diaphragm, also uncovered by peritoneum : around this place 
of contact, the peritoneum is extended from the diaphragm to 
the liver, and thus forms what has been called the coronary liga- 
ment of the liver. 

The peritoneum of the right side of the diaphragm, and of the 
abdominal muscles, as far down as the umbilicus, is extended to 
the liver, and joins it on the convex surface immediately opposite 
to the umbilical fissure. The peritoneum from the left side of 
these parts does the same; and as these reflections of the perito- 
neum are continued from so low a part as the umbilicus, they 
arc extended not only to the convex surface of the liver, but also 
to the great notch, and along the umbilical fissure. 

From the umbilicus proceeds a round cord-like ligament, 
which in the fetal state was a vein, that passes to the great fis- 
sure of the liver, and along it. The process of the peritoneum 
above mentioned is so connected with this cord, that it encloses 
it in its lower edge, and the whole is called the falciform liga- 
ment of the liver. The cord, when named separately, is the 
umbilical or the round ligament; and the membrane or lamina of 
the peritoneum forms the suspensory ligament. Besides these, 
the peritoneum on the lower side of the liver is so arranged, that 



1WODC OF SUPPORTING THE LIVER. g^ 

it not only extends to the stomach, but to the duodenum and the 
colon. 

By these ligaments the position of the liver must be fixed to 
a great degree; and there is one additional connexion, which 
must have a great effect in retaining it in its proper situation. 
The vena cava receives two or three great veins from' the liver, 
(vence cavce hepaticce,) at the place where it is in contact with the 
posterior edge of that viscus: these veins of course pass directly 
from the substance of the liver into the cava, and connect it to that 
vessel. As the cava is supported by the heart, and also by the 
diaphragm, it must afford a considerable support to the liver. 

When the stomach and intestines are distended, they must 
also contribute in a considerable degree to the support of the 
liver. 

The liver has a strong tendency, when we are erect, to change 
its situation ; and some considerable support is necessary to 
counteract this tendency. It would move to the right, when we 
lie on the right side, if it were not in contact with the ribs : and 
it inclines to the left, for want of such support, when we lie on 
the left side. 

It has been computed, that the liver descends about two inches, 
when the position of the subject is changed from the horizontal 
to the erect. As it is in contact with the diaphragm, it is obvi- 
ous that it must be influenced by the motions of that muscle, and 
that it must descend when the diaphragm contracts. 

The liver is composed of a substance which has some firm- 
ness of consistence, although it is yielding; and is also somewhat 
brittle or friable.* When cut into, the sections of many tubes, 
or vessels of different diameters, appear on the cut surface. 
When the texture of this substance is more closely examined, it 
appears somewhat granulated, or composed of very small bodies, 
which were called acini by the anatomist who first described 
them. The whole substance is enclosed by the peritoneum, 
which is extended to it from the surface of the abdomen in the 
manner that has been already described. It has also a proper 

* It has been fractured in the living body by external violence. 



$g VESSELS OF THE LIVER—HEPATIC ARTERY. 

coat or capsule ; and on the posterior edge, where the lamina of 
the lateral ligaments pass from the diaphragm to the liver, at 
some distance from each other, a portion of the liver, covered 
by this coat and by cellular substance, is in contact with the 
diaphragm. The same thing occurs likewise at the coronary 
ligament.* 

The liver holds the first place among the glands of the body 
for size, but it is still more remarkable for some other circum- 
stances in its economy. In addition to an artery, which passes 
to it as arteries do to other glands, there is a large vein, (vena 
portarum,) which also enters it as an artery ; and after ramifying 
throughout the liver, communicates, as does the artery, with 
other veins, which carry the blood from this gland into the vena 
cava and the general circulation. There are therefore three 
species of blood-vessels in the liver ; and with these are found 
the vessels which carry out of the gland the fluid secreted by 
it, or the bile. 

The artery of the liver is denominated the Hepatic Artery. 
The vein which goes to the liver is called the Vena Portarum, 
from the place at which it enters. The veins which carry to the 
vena cava the blood brought to the liver by the hepatic artery 
and the vena portarum, are called the Hepatic Veins ; and the 
duct through which the bile flows out of the liver, is called the 
Hepatic Duct. Three of these vessels, the Hepatic Artery, the 
Vena Portarum, and the Hepatic Duct, enter the liver at the 
great fissure, at the spot where the prominences exist called the 
portse ; hence the name vena portarum was applied to the vein. 

These vessels ramify in the manner presently to be described ; 
and it is ascertained by minute anatomical investigation, that the 
liver is entirely composed of the ramifications of these vessels 
and of the hepatic veins, with absorbent vessels and nerves, 
which are connected together by cellular membrane. 

It has been already observed, that the first great branch sent 

* Many anatomists deny the existence of this coat; but if one of the lamina of 
the ligaments be carefully peeled off from the surface of the liver which is slightly 
affected by putrefaction, it will be apparent, although very thin. It was described 
by M. Laennec, in Le Journal dc Medicine for 1803. 



VENA PORTARUM. 89 

off by the aorta in the abdomen, the Casliac, divides into three 
branches, which go respectively to the stomach, the liver and 
the spleen. 

The Hepatic is generally the largest of these branches. In its 
progress towards the liver it sends off an artery to the stomach, 
called the gastrica dextra. At the great fissure it divides into 
two branches : the right branch, which supplies the right lobe of 
the liver, is of course the largest. This branch sends off one to 
the gall-bladder, which is called the cystic artery; and also 
some smaller branches: it passes under the hepatic duct, and 
ramifies through the great lobe of the liver. The left branch is 
distributed through the left lobe of the viscus. It can be proved 
by injection, that the hepatic artery communicates not only with 
the hepatic veins, but with the biliary duct, and the vena porta- 
rum also. It has been disputed whether the size of this artery 
is greater than would be requisite for the nourishment and ani- 
mation of the liver. 

The Vena Portarum, the great peculiarity of the liver, origi- 
nates from all the chylopoietic viscera except the liver, and is of 
course formed by the union of the veins which correspond to all 
the branches of the coeliac and mesenteric arteries, as they are 
distributed to the stomach and intestines, the spleen, the pancreas, 
and the omentum. The veins from the intestines generally form 
two great trunks, which are denominated the greater and lesser 
mesenteric veins. The great mesenteric vein is situated to the 
right, and rather before the mesenteric artery. — After it has ap- 
proached the origin of the artery, it separates from it, and passes 
behind the pancreas : at this place, nearly in front of the spine, 
it is joined by the great vein of the spleen, which forms almost a 
right angle with it, and these constitute the great trunk of the 
vena portarum. The lesser mesenteric vein, which corresponds 
to the inferior mesenteric artery, and brings blood from the pelvis 
and from the left part of the colon, becomes finally a large vessel, 
and commonly unites with the splenic about an inch and a half 
before its junction with the superior mesenteric vein. The vena 
portarum, thus formed, proceeds towards the liver, inclining to 
the right, and is generally about three inches in length: in its 

8* 



,jq VENA PORTARCM -HEPATIC DUCT. 

course it sometimes receives small veins, which in other cases 
pass to its splenic and mesenteric branches. When it has arrived 
at the great transverse sinus of the liver, it divides into two large 
branches, each of which forms nearly a right angle with it. 
Their size is so great, that, when distended with injection, they 
appear like an independent vessel, into which the vena portarum 
enters ; and on this account they are called the Great Sinus of 
the vena portarum. They do not adhere firmly to the glandular 
substance of the liver, but are united to it by cellular membrane. 
The right branch is the widest and shortest. It generally 
divides into three branches ; an anterior, a posterior, and a late- 
ral branch; which ramify minutely, and extend themselves in 
the right lobe. The left branch is much longer, and continues 
to the extent of the transverse < fissure. Near its termination it is 
joined by the umbilical ligament, which has been already men- 
tioned. This branch is generally in contact with a branch of 
the hepatic artery, and of the hepatic duct; and ramifies like the 
right branch, into the contiguous parts of the liver. 

The Hepatic or excretory duct originates, by very small 
vessels, from the acini or corpuscles of which the liver is com- 
posed, and into which the minute ramifications of the vena 
portarum and hepatic artery extend. They accompany these 
vessels, increasing as they increase, although the fluid they con- 
tain moves in an opposite direction ; and two large branches 
which they ultimately form are situated at the porta? of the liver, 
in contact with the great branches of the vena portarum and the 
hepatic artery. 

These three vessels are in contact with each other before they 
enter the liver. The biliary duct is anterior, the vena portarum 
posterior, and the artery to the left of them. They are accom- 
panied by nerves and lymphatic vessels, and are surrounded by 
a considerable quantity of cellular substance, and thus arranged 
are partially covered with peritoneum. The cellular substance 
which invests them continues with them into the liver, and is 
more particularly connected with the vena portarum. It is called 
Glisson's Capsule, and was supposed to have some contractile 
power, which assisted the circulation of the vena portarum ; but 
that idea is now altogether abandoned. The hepatic veins. 



HEPATIC VEINS.-NERVES OF THE LIVER 9J 

which receive the blood of the hepatic artery and the vena por- 
tarum, open into the anterior part of the vena cava, where it is 
in contact with the liver. Generally there are three of these 
veins, but sometimes there are only two; in which case one of 
them is formed by two others, which unite immediately before 
they open into the vena cava. It is to be observed, that the various 
branches of these veins do not accompany those branches of the 
vena portarum or hepatic artery to which they correspond, but 
form very large angles with them. This is probably owing 
merely to their termination in a part so distant from that in 
which the artery and the vena portarum originate; but it is very 
different from what occurs in other glands. 

The Nerves of the Liver are derived from the semilunar gan- 
glions of the splanchnic nerves. From these many nerves pro- 
ceed, which form a net-work denominated the solar plexus. 
From this plexus many threads are sent oft', which form a net- 
work that is divided into the right and left hepatic plexus. These 
plexuses surround the hepatic artery and the vena portarum, and 
accompany them in their ramifications throughout the liver, 
being enclosed by Glisson's capsule. They receive some threads 
from the stomachic plexus, formed by the par vagum. Although 
the number of nervous fibres is very considerable, their bulk, 
compared with that of the liver, is very small. 

The Lymphatics of the Liver are extremely numerous ; and 
those in that portion of the peritoneum which invests the liver 
may easily be rendered conspicuous: for by pressure the injected 
fluid can be forced from the trunks and large branches into the 
small ramifications, in opposition to the valves. When all the 
surface is injected in this manner, it has the colour of the sub- 
stance injected ; as is the case with parts which are very vas- 
cular, when the blood-vessels are injected. 

The deep-seated lymphatics are also very numerous in the 
liver, and communicate freely with the superficial. 

The superficial lymphatics, which are on the upper surface, 
proceed through the diaphragm into the thorax in their course 
to the thoracic duct. Those which are deep-seated emerge from 
the liver at the porta?, where the great vessels enter, and unite 
with the thoracic duct in the abdomen, after passing through 



Q2 GLANDULAR SUBSTANCE OF THE LIVER. 

several glands. The lymphatics of the lower surface unite with 
the deep-seated. 

The glandular or parenchymatous substance of the liver is of 
a reddish-brown colour, and moderately firm consistence. When 
it is cut into, the cut surface exhibits the sections of the branches 
of the different blood-vessels above mentioned, and of the ex- 
cretory ducts. These vessels are often distinguishable from each 
other. The section of the biliary duct appears the thickest ; that 
of the artery next ; the vena portarum is next in order ; and, 
last of all, the venae hepaticae. 

The branches of the vena portarum are surrounded by cellular 
substance, or Glisson's capsule ; and, therefore, adhere less to 
the substance of the liver than the branches of the hepatic veins. 
The sections of the hepatic ducts have often bile in them, and 
are, therefore, termed pori biliarii. The branches of the artery 
are also very distinguishable. 

When the internal substance of the liver is brought into view, 
and examined accurately, it appears to be formed of small bodies, 
or acini, which are distinguishable from each other. If the liver 
happens to be torn or lacerated, the lacerated surfaces are rough 
and irregular, owing to the separation of these acini from each 
other.* 

It is asserted by several microscopical observers, that a minute 
branch of each of the aforesaid vessels can be traced into each 
of the acini. It is also declared, that if each of these vessels be 
injected separately with mercury, oil of turpentine coloured, or 
a saturated aqueous solution of gutta gamba, there is no part of 
the glandular mass as large as a grain of mustard seed in which 
those vessels will not be found. 

Several anatomists of the first character have likewise de- 
clared, that a fluid properly injected into one of these vessels, 
will occasionally pass into all of them. Thus an injection will 
not only pass from the vena portarum to the biliary duct, but to 

* The acini are so named from a fancied resemblance to grape or raisin seeds. 
Between these acini, there is usually a minute quantity of fatty matter, the 
existence of which is proved by the destructive analysis of the organ. In tubercular 
phthisis, especially in females, it occasionally accumulates so as to form what is called 
the fatty liver, which presents a mottled appearance, and resembles much the livers 
of the shark, cod, and other oily fishes. — r. 



OF THE ACINI 93 

the hepatic artery and veins also. It will likewise pass, in a 
retrograde course, from the biliary ducts to the vena portarum, 
and to the hepatic artery and the hepatic veins ; or from any one 
of the four orders of vessels into the three others.* 

The great peculiarity of the liver is, that venous blood, instead 
of arterial, is brought to it for the purpose of secretion. Thus 
the great vein of the chylopoietic viscera, instead of passing to 
the cava, enters the liver by the transverse fissure, and takes on 
the office of an artery ; its coats, on this account, being much 
thicker and stronger than those of the hepatic veins.f 

— The acini, when isolated from the surrounding granulations, 
and examined with a simple microscope, appear evidently to be 
ovoid, or rather polyhedrical bodies, with five or six facets, so 
arranged as to fit exactly to the facets of the surrounding acini, 
leaving no interval between them, except that occupied by the 
intervening delicate cellular tissue, which is an extension from 
the capsule of Glisson. 

— Miiller, in a few cases succeeded in injecting the biliary canals 
from the hepatic duct, with size coloured with vermilion, so as 
to make the liver quite red. The minute acini were then seen to 
be formed of ramified divisions of the biliary ducts, which termi- 
nate in the acini in a tuft of vessels, which divide without dimin- 
ishing in size, and anastomose together so as to form a net-work. 
They lie ciose together, and are difficult to be discovered, even 
with the microscope ; their diameter varies according to Muller, 
from j} s th to T | 7 th part of an inch, but is greater, however, 
than that of the capillary vessels. 

— According to Kiernan.J who has investigated this subject with 
much care, the small granular bodies, so well known to anatomists 
in the liver under the name of acini, should be called lobules, 
inasmuch as they are found when examined under the micro- 

* I have tried the experiment, and find the assertion to be correct. — h. 

t A case is related by Mr. Abernethy, in the London Philosophical Transactions, 
in which the vena portarum terminated in the vena cava below the liver, without 
communicating with it. The hepatic artery was the only vessel which carried 
blood to the organ, and was unusually large, the liver being nearly of the natural 
size. Some bile was in the gall-bladder, but it was less acrid than usual. 

t Kiernan, on the Anatomy and Physiology of the Liver, Philosophical Trans, 
actions of the Royal Society of London, for 1833.— -p. 



94 



KIERNAN ON THE MINUTE 



scope, to be apparently composed of numerous smaller bodies, 
coloured yellow most generally by the bile which they contain. 

Fig. 53.* 




--a 



Each of these lobules of Kiernan, {acini of most other anato- 
mists) is composed according to him, of a plexus of biliary 
ducts, (see Fig. 53,) and a plexus from the portal vein, placed 
on its exterior surface, (see Fig. 54,) of branches of the he- 
patic artery, and of a branch of a hepatic vein, which oc- 
cupies its centre, (see Fig. 55.) Nerves and absorbents, it 
is also probable, enter into its structure, but they cannot be 
traced upon it. The plexuses formed by the hepatic ducts 
in each lobule, may be called the lobular biliary, or se- 
creting biliary plexuses. The ducts forming them being ex- 
ceedingly minute, and anastomosing very freely with each other, 
as seen in Fig. 53. At their termination, they appear to have no 
communication with the veins, and hence it is difficult to inject 
these plexuses with mercury or size, since they generally contain 
bile which has no place of escape, and which prevents the injecting 

* Fig. 53, represents the interlobular ducts, entering the lobules, and forming the 
lobular biliary plexuses, a, Two lobules, bbb, Interlobular ducts, cce, The 
interlobular cellular tissue, d d, The external portions of the lobular biliary plex- 
uses injected, e e, The intralobular branches of the hepatic vein. //, The unin- 
jected central portions of the lobules. Mr. Kiernan, has never injected the lobular 
biliary plexuses, to the extent represented in the cut. It is, therefore, to be con- 
sidered rather as a diagram, illustrating the structure, in accordance with the re- 
sults of his different observations and experiments. — p. 



ANATOMY OF THE LIVER. 

Fig. 54 * 



95 



-b^fkg? .'* 




Fig. 55.f 




.-- c 



fiuid in ordinary cases from filling minutely the lobular plexuses. 
The space between these anastomosing 
ducts, he considers identical with the 
acini of Malpighi, which this anatomist 
has but obscurely described, and which, 
examined through the microscope, have a.- 
likewise the appearance of the cells deli- 
neated by Mascagni. The lining mem- b 
brane of the hepatic ducts, like other mucous membranes, pos- 

* Fi<r. 54, represents the interlobular branches of the portal vein, the lobular 
venous plexuses of the intralobular branches of the hepatic veins of these lobules. 
a a a, Interlobular veins contained in the spaces, b b b, The interlobular veins 
of the fissures and which with the veins in the spaces, form venous circles 
round the lobules. This is the appearance which the venous circles present when 
examined with a common magnifying glass. They are, however, formed by 
numerous, and not by single branches, as represented in the figure, c c c, The 
lobular venous plexuses, the branches of which communicating with each other by 
intermediate vessels, terminate in the intralobular veins. The circular and ovoid 
spaces seen between the branches of the plexuses, arc occupied by portions of the 
biliary plexuses, constituting the acini of Malpighi. d d cl, The intralobular 
branches of the hepatic veins, in which the vessels of the plexuses terminate. — p. 

t 55, «, A transverse section of a lobule. 6, The divided central intralobular 
vein, c, The small veins, terminating in a central vein. — r. 



gg KIERNAN ON THE 

sesses many mucous follicles, as seen in Fig. 56. They are here 
arranged in rows, and from them is derived all the 
mucus that is admixed with the bile. In each lobule, 
the portal veins ramify, as seen in Fig. 54, among 
the branches of the biliary plexus, and finally termi- 
nate near the centre of each lobule in the hepatic 
veins. The hepatic veins are very peculiar. A branch 
arises from the centre of each lobule, as seen in Fig. 
57; and each intralobular branch divides into several 
capillary filaments, fo receive the blood of the portal 
branches, so that each lobule seems to be placed upon 
one of the branches of the hepatic veins, as a leaf 
upon its central stem. 
— Each of these branches opens by a minute orifice, directly 
into one of the divisions of the venae cavae hepaticae, this system of 




Fig. 57.f 




veins having no cellular sheath, or 
capsule surrounding it, as is the 
case with the vena porta, but is 
directly in contact, throughout its 
whole course in the liver with the 
bases of the lobules. The hepatic 
arteries, distribute their branches 
in the coats, of the hepatic ducts, 
of the venaportarum and of the he- 
patic veins ; and the veins in which 
these arterial capillaries terminate, 
always consist, according to Mr. Kiernan, of the radical branches 
of the vena portarum. Thus, the hepatic arteries, and the portal 
branches form the vasa vasorum of all the different vessels and 
ducts of the liver, and all the blood of the hepatic arteries, passes 
first into the portal system and thence into the hepatic veins, in 

* Fig. 56, represents the internal surface of a small hepatic duct, with its fol- 
licles arranged in two longitudinal lines. — p. 

t Fig. 57, A, An hepatic vein. B, Lobules arranged around the intralobular 
branches of the hepatic veins, as they are frequently seen at the posterior part of 
the concave surface of the liver. This arrangement is more distinctly seen in the 
liver of the sheep than in the human liver. These lobules arc parallel to the 
surface. — p. 



MINUTE STRUCTURE OF THE LTVER. 97 

its circulation through the liver. For these reasons, Mr. Kiernan 
believes the bile secreted solely from the blood of the portal 
veins. For even in the well known case mentioned by Mr. 
Abernethy, where the vena porta terminated in the vena cava 
without passing through the liver, he found the hepatic arteries 
much larger than usual, and the portal branches into which they 
terminated in their course through the liver of corresponding de- 
velopement; so that even in cases of that sort, the biliary secretion 
is made not from arterial blood, but from that of the portal veins. 
The capsule of Glisson is a cellular sheath which extends around 
the hepatic artery, vein and duct, accompanying their minutest 
ramifications, up to the lobules, and terminates by forming a 
delicate capsular investment to each of the individual lobules. 
It serves, according to Kiernan. like the pia mater of the brain, 
as a nidus or bed in which the larger branches of these ves- 
sels may subdivide before entering into the delicate structure 
of the lobules. In the interlobular spaces, filled up with the 
tissue, the portal veins form a sort of vascular circle as seen in 
Fig. 53. 

— It has been asserted by Ferrein, Autenreith, Andral and others, 
that there are two substances in the liver, a cortical and medul- 
lary, or red and yellew; the former of which was exterior and 
the latter central, in each lobule. This has been denied by Cru- 
veilhier and Miiller ; and Kiernan has shown that this difference 
in colour, depends upon the separate congestion of one of the 
different system of vessels, for such is the great vascularity of 
the liver that it is usual after death to find one or other in a 
state of congestion. By injecting moderately, a coloured fluid 
into the hepatic veins, he found he could colour red, even in the 
healthiest liver, the central parts of the lobules; by using more 
force he could colour the whole substance of the lobule, by the 
blood passing into the portal banches. By injecting into the 
portal system under similar circumstances, the outer part of the 
lobule was first coloured. The yellow colour of these acini or 
lobules is owing, according to Cruveilhier, to a congestion of 
bile in the radicles of the biliary ducts. The opinions of this 
anatomist coincide in the main in regard to the structure of the 
vol. 11. 9 



gg HEPATIC DUCT. 

acini, with those of Mr. Kiernan. He believes, however, that 
the termination or rather origin of the branches of the biliary 
duct is from the centre of each acinus, and that immediately 
around this is a vascular circle formed by the radicles of the 
hepatic intralobular vein, while the portal system forms a circle 
extrinsic to the whole. He also believes that there is a part of 
the outer surface of each lobule, which is uninjectable, spongy 
and porous, and serves the part of a filter.* 

The Biliary or Hepatic Duct is formed of very minute vessels, 
which originate in the acini above described : these unite together 
like veins until they form considerable branches, which finally 
compose the great ramifications of the biliary duct. This duct 
is very strong and firm, and on its internal surface are the ori- 
fices of many mucous follicles or ducts. It passes from the 
transverse fissure of the liver, with the hepatic artery, as before 
described, and at the distance of an inch and a half or two inches 
from the fissure, it unites with a duct from the gall-bladder, 
which is called the Cystic Duct. This duct is nearly equal in 
length to the hepatic, and after running almost parallel to it, at 
length unites so as to form an acute angle with it. The cystic 
duct is smaller than the hepatic, and they unite much like two 
branches of an artery. 

The Gail-Bladder, from which the cystic duct arises, has the 
shape of a pear, with a very long neck, curved in a way to be 
hereafter described. It is situated in a superficial pit or cavity 
in the concave surface of the right lobe of the liver ; and its 
fundus, or basis, often projects a small distance beyond the ante- 
rior edge of the viscus. Its position is such, that it extends from 
before backwards, and inclines rather to the left ; of course, 
therefore, when the subject lies on his back, the bottom of the 
bladder is the uppermost part of it : when he lies on the left side, 
it is also higher than the neck ; and when he lies on the right 
side it is the lowermost. 

The gall-bladder consists of an internal coat, and one that is 
cellular or nervous, and has somewhat of a fibrous appearance. 
This coat connects the gall-bladder to the surface of the pit or 

* Anat. Descript. T.ii. p. 575. 



GALLBLADDER. ,,q 

cavity in which it lies. The peritoneal coat of the liver is ex- 
tended from the surface of the viscus over that part of the surface 
of the gall-bladder which is .not in contact with it. 

The internal coat has a peculiar structure, with a faint re- 
semblance to that of the villous membrane. It is so arranged as 
to form very fine folds, which have various directions : in some 
places they make a net-work ; in others, as the neck of the 
bladder, they are longitudinal. Many mucous follicles exist on 
its internal surface. 

The neck of the gall-bladder is suddenly bent down or curved 
upon itself, and twisted, so that it resembles the neck of the 
swan, when the head of that bird is applied to one side of its 
breast. 

A branch of the hepatic artery, which leaves it before it enters 
the liver, is appropriated to the gall-bladder, and is, therefore, 
denominated the cystic artery. The veins corresponding to this 
artery empty themselves into the vena portarum.* The lymphatic 
vessels are united to those which are found on the lower surface 
of the liver, and the nerves are derived from the hepatic plexus. 

The gall-bladder appears to be merely a reservoir, into which 
bile passes through its duct in a retrograde direction. If air be 
blown through the hepatic duct from the liver, it will pass to the 
gall-bladder almost as freely as it passes to the duodenum. 

The biliary duct from the liver, after receiving the duct from 
the gall-bladder, takes the name of Ductus Communis Choledo* 
chus. It is wider than either of the other ducts and near three 
inches in length. It passes down before the vena portarum, and 
on the right of the hepatic artery, to the posterior surface of the 
right extremity of the pancreas. It passes through a small por- 
tion of that gland, and then perforates the muscular coat of the 
duodenum ; after which it proceeds from half an inch to an inch 
between this coal and the villous, and opens into the cavity of 
the intestine. The orifice forms a tubercle which extends length- 
wise of the intestine, and is rounded above and pointed below, 
with a slit in it. While this duct is in contact with the pancreas, 

* It has been justly observed by John Bell, that the veins would not tenninato 
thus, if bile were secreted by the gall-bladder. 



100 THE PANCREAS. 

a duct from that gland generally opens into it, so that the biliary 
and pancreatic fluids enter the duodenum by the same orifice; 
but sometimes the pancreatic duct opens into the duodenum, by 
a distinct orifice, very near to that of the biliary duct. 

The Bile, or fluid secreted by the liver, appears to answer a twofold purpose 
in the animal economy. It produces a chemical effect upon the alimen- 
tary mixture which passes from the stomach through the intestines; and 
it increases the peristaltic motion of those important organs. 

By an inverted action of the duodenum, some of this fluid is frequently car- 
ried upwards into the stomach : it then often produces only slight derange- 
ment of the functions and sensations connected with that viscus ; but 
sometimes violent vertigo, and even convulsions, seem to have arisen 
merely from the presence of a large quantity of bile in the stomach : for 
they have gone off completely upon the discharge of bile by vomiting. 

Notwithstanding these effects of bile in certain cases, in which a great deal 
of it exists in the stomach, it is often carried into the mass of blood in 
large quantities, and appears to be mixed with the serum, and to circulate 
through the body, without producing any very sensible effect : thus many 
persons who are deeply tinged by bile in their blood, experience but few 
effects that qan be imputed to the mixture of it with the circulating fluids: 
and neither the brain nor the heart appears to be much influenced by the 
circumstance. 

Bile is miscible with water and with alcohol, and also with oily substances ; 
and it often assumes a green colour, when mixed with acids. The colour 
of the alvine discharges is derived from the bile, and they are therefore 
sometimes very green, when the acetous fermentation takes place in the 
contents of the stomach and bowels. 

It is asserted by some chemists, that ten parts in eleven of the human bile 
consist of water; that albuminous matter composes about one-forty -sixth 
part of it ; and that there is nearly an equal quantity of resinous mater in 
it. There is also a small quantity, (one part in 244,) of uncombined soda 
dissolved in it, and a small quantity of neutral salts, consisting of soda 
combined with the phosphoric, sulphuric and muriatic acids. In addition 
to these is a very small quantity of phosphate of lime and of oxide of iron, 
and some yellow insoluble matter. 

The bile in the Gall-Bladder is generally more viscid than that which is 
found in the Hepatic Duct. 

Of the Pancreas. 

The pancreas is a glandular body, which has a strong resem- 
blance to the salivary glands in several particulars. It is seven 



THE PANCREAS. 101 

inches in length, and is irregularly oblong in its form, one extre- 
mity being much larger than the other. Its large extremity is in 
contact with the duodenum, and it extends from this intestine in 
a transverse direction to the spleen, to which it is connected by 
the omentum and by blood-vessels. It is not invested by the pe- 
ritoneum, but is situated in the space which exists between the 
two lamina of the mesocolon, as they proceed from the back of 
the abdomen, before they come in contact with each other. It 
is anterior to the aorta and vena cava, and to the mesenteric 
vein, or main branch of the vena portarum ; being connected to 
these parts by cellular membrane. At the right extremity, 
which is connected with the duodenum, is a process of the gland 
that extends downwards in close contact with the intestine. This 
is called the head of the pancreas, or the lesser pancreas. 

The position of the pancreas is such, that one of its surfaces 
looks forwards and rather upwards, and the other backwards 
and downwards ; one edge is of course posterior and superior, 
and the other interior and inferior. The posterior of these edges 
is much thicker than the other, and has a groove or excavation 
which is occupied by the splenic blood-vessels. 

This gland differs from the other large glands of the abdomen, 
inasmuch as it has not a large artery particularly appropriated 
to it; but instead of this, it receives branches from the contigu- 
ous arteries. 

The arterial blood of this gland is partly supplied by the 
splenic artery, which, in its course from the main trunk of the 
cceliac to the spleen, while it is in the groove at the edge of the 
pancreas, sends off into the gland one considerable branch called 
the great pancreatic, and a number of small branches, which go 
off in succession. In addition to these, the pancreas receives 
vessels from one of the branches of the hepatic artery, before it 
sends off its great ramifications, as well as small twigs from 
several other contiguous arteries. The veins correspond with 
the arteries, but ultimately are discharged into the vena por- 
tarum. 

The pancreas resembles the salivary glands in colour, and 

<) • 



1 02 PANCREATIC DUCT. 

also in texture ; for it is of a dull white colour with a tinge of 
red, and it appears to consist of small bodies of a granulated 
form, which ale so arranged as to compose small masses or 
lobes that are united to each other by cellular membrane. Each 
of these granulated bodies receives one or more small arterial 
twigs, and from it proceeds not only a vein but a small excretory 
duct, which, uniting with similar ducts from the adjoining gra- 
nulated portions or acini, forms a larger duct in each lobe or 
mass ; these open into the great duct of the gland, which pro- 
ceeds through it lengthwise from the left extremity, in which it 
commences, to the right. 

This duct is situated in the body of the gland, which must be 
dissected to bring it into view. It is thin and transparent, like 
the ducts of the salivary glands, and is rather larger in diameter 
than a crow's quill. In its progress towards the right extremity 
of the gland, it gradually enlarges, and commonly receives a 
branch from the part called the lesser pancreas. It most com- 
monly unites with the biliary duct before it opens into the duode- 
num : sometimes these ducts open separately, but very near to 
each other. They penetrate the coats of the intestine, rather ob- 
liquely, and between four and five inches from the pylorus. This 
canal is sometimes called Ductus Virsungii, after an anatomist 
who published a plate of it. 

The pancreas has an irregular surface, and no coat which 
covers it uniformly. It is invested by cellular membrane, which 
also connects its different lobes to each other. Absorbent ves- 
sels and nerves are traced into it. 

The portion called the lesser pancreas adheres to the duode- 
dum, and when it is enlarged by disease, the passage of aliment 
through that intestine is much impeded, and sometimes complete- 
ly obstructed.* 

It is now generally believed that the fluid secreted by the pan- 
creas is similar to that which is produced by the salivary glands. 

* In several cases where examination after death evinced that the pancreas had 
become enlarged and indurated, particularly at the right extremity, the principal 
symptoms were jaundice ; great uneasiness after talcing food ; vomiting some time 
after eating, but not immediately ; extreme acidity of the matter rejected. 



OF THE SPLEEN. JQ3 

Size of the Spleen. 

The spleen is a flat body of a bluish colour, and an irregular 
oblong form, with thick edges, which are indented in some 
places. 

It is various in different subjects, both in size and form. Its 
most common size is between four and five inches in length, and 
about three or four inches in breadth ; but it has often been found 
of more than four times this size; and it has also been seen 
not much longer than an inch. Its ordinary weight is between 
six and nine ounces ; but it has varied in different subjects from 
eleven pounds to one ounce. It is supposed, by many physiolo- 
gists, that it frequently varies in size in the same individual. 

It is situated in the left hypochondriac region, in contact with 
the diaphragm, below the eighth rib. The position of the spleen 
is somewhat oblique, — one extremity being directed downwards 
and rather forwards, and the other upwards and backwards; 
but when the stomach is distended, the lower end of it is pushed 
forward by the great extremity of that viscus. 

In general it is so deeply seated in the left hypochondriac re- 
gion, that it is out of view when the subject is opened in the or- 
dinary way : but in some cases of enlargement, after the inter- 
mitting fever, it has extended downwards, nearly as low as the 
pelvis; and towards the right side beyond the umbilicus. 

The external surface of the spleen is convex, in conformity to 
the surface of the diaphragm, with which it is in contact. The 
internal surface of the spleen is irregularly concave, having a 
longitudinal fissure which divides it into two portions. 

The spleen is invested by the peritoneum, one process of which 
is often extended from the diaphragm, above and behind it, in 
the form of ligament. Another process of the same membrane 
is extended to it from the great extremity of the stomach. The 
peritoneum is also continued from the spleen in the form of 
omentum, (gastro-spknic.) 

Within this peritoneal covering is the proper coat of the spleen, 
which is so closely connected to it, that many anatomists have 
considered them as one membrane : they are, however, very 



104 VESSELS OF THE SPLEEN. 

distinct at the great fissure, but the external coat is extremely 
thin. 

The proper coat of the spleen is not very thick ; it is dense 
and firm, and somewhat elastic, but not much so. It is partly 
transparent. 

The spleen has a large artery, which is one of the three great 
branches of the cceliac. This vessel runs in an undulating man- 
ner in a groove in the upper edge of the pancreas, and in this 
course sends off many small branches to supply that gland. 
The splenic artery, before it arrives at the spleen, divides into 
five or six branches, which are also undulating in their progress, 
and penetrate into the body of the viscus at the above mentioned 
fissure. These branches are distributed to every part of the 
viscus, and ramify minutely. 

From these branches, or from the main trunk before it rami- 
fies, three or four smaller branches proceed to the left extre- 
mity of the stomach. They are called vasa brevia or arterise 
breves. 

The arteries which enter the spleen are accompanied by veins 
that emerge from it, and unite to form a great trunk. This 
trunk observes a course corresponding to that of the splenic 
artery, and receives veins from the stomach and pancreas, which 
correspond with the arterial branches sent to those organs. The 
splenic vein is one of the principal branches of the vena por- 
tarum. 

The splenic artery is very large in proportion to the viscus to 
which it is sent, and the vein is unusually large in proportion to 
the artery. The vein is also very tender and delicate in its 
structure. 

The absorbent vessels of the spleen are very numerous. It has 
been asserted, that when those of the external coat of the spleen 
are injected, they are sufficient to form a fine net-work on it. 
The absorbents of the deep-seated parts unite to the superficial 
at the fissure where the blood-vessels enter. They terminate in 
the thoracic duct, after passing through several lymphatic glands. 
The nerves of the spleen are derived from the solar plexus : 
they form the plexus around the vessels, and accompany them 
through the viscus. 



MALPIGHI ON THE STRUCTURE OF THE SPLEEN. 



105 



The spleen consists of a substance which is much softer than 
that of any other viscus of the abdomen. This substance is 
made up either wholly or in great part of the ramifications of 
the splenic artery and vein, which are demonstrated by injections 
to be very minute and numerous in this body. There are also 
many fine white cords, like threads, which pass from the internal 
surface of the inner coat of the spleen in its soft substance, in 
which some of them ramify. These cords connect the substance 
of the spleen pretty firmly to its coat, and they seem to have 
the effect of rendering the exterior part of the substance more 
firm and dense than the internal. They are particularly con- 
spicuous if the spleen be immersed in water, and the coat pulled 
off while it is in that situation. 

The spleen has a strong resemblance to the glandular organs, 
but has no excretory duct, and its particular function is not very 
obvious: for these reasons the structure of this organ is a sub- 
ject of very interesting inquiry. 

Malpighi, who took the lead in researches of this nature, be- 
fore injections of the blood-vessels with wax were in use, after 
investigating the structure of the spleen by long maceration, by 
boiling, by inflation, by the injection of ink or coloured fluids, 
and by examination with microscopes, declared that its structure 
was cellular; that the cells communicated more freely with 
the veins than the arteries ; and that they might be considered 
as appendices of the veins. He also asserted, that a large num- 
ber of white bodies or vesicles were to be found in those cells 
and throughout the whole substance of the spleen, which were 
in bunches like grapes, and preserved their whitish colour although 
the vessels around them were injected with a coloured fluid. 
This description of Malpighi appears to have been admitted by 
some of the very respectable anatomists who were contempo- 
rary with him ; but it was zealously opposed by Ruysch, who 
exhibited the spleen so completely injected with wax, that it ap- 
peared to be composed entirely of vessels.* 

* Two plates, taken from drawings of these preparations are published in 
Ruysch's Works. One is attached to Epistola Problematica Quarta, in the second 
volume; and the other in Thesaurus Septimus, in the third volume. 



106 RUYSCH AND DE LA SONE ON THE SPLEEN. 

Ruysch appears to have paid great attention to this subject, 
and to have made many preparations of the spleen. From these 
he derived the opinion, that the substance of this organ was en- 
tirely composed of arteries, veins, absorbent vessels and nerves ; 
and that if it were properly injected before it was dissected, no 
other structure would be found. He stated, that the minute rami- 
fications of the blood-vessels appeared to have acquired a pecu- 
liar quality, and were so soft and delicate that their texture was 
destroyed by the least friction; and that by the slightest degree 
of putrefaction they appeared to be reduced to a fluid state. He 
also denied the existence of cells, or of the whitish bodies de- 
scribed by Malpighi. 

The question thus at issue between these great masters of their 
art was very carefully examined by M. De La Sone* a French 
Physician, whose observations are published in the Memoirs of 
the Academy of Sciences for 1754. After repeating the pro- 
cesses of each of these anatomists, and instituting some others 
in addition, he adopted the opinion that there was in the texture 
of the spleen, a pulpy substance which was not a mere coagu- 
lum, but which, however, could not be injected. 

He derived this opinion from this fact among others. After 
macerating the spleen a considerable time, and injecting water 
into the vessels until it returned colourless, he injected ink, and 
confined it some time in the vessels by tying them : he then al- 
lowed the ink to flow out of the vessels, and made various sec- 
tions of the spleen; but no ink appeared in the pulpy substance, 
although it was visible in many small vessels which ramified in 
that substance. He observed that this could not have been 
the case, if the pulpy substance had been composed entirely of 
vessels, as was supposed by Ruysch. 

He also examined the spleen after it had been injected with 
wax, according to the manner of Ruysch, and believed not only 
that the pulpy matter remained uninjected, but that Ruysch 
himself, in his own preparations, removed this substance, suppos- 
ing it to exist for the mere purpose of connecting the vessels to 
each other. 



HALLER AND THE FRENCH ANATOMISTS ON THE SPLEEN. 



107 



To see the blood-vessels in the same state of distention in 
which they were during life, he tied the splenic vessels in a living 
animal, and removed the spleen with the ligatures on the vessels. 
In this situation he boiled it, and then examined the appearance 
of the vessels and the pulpy substance. — From these, as well as 
his other observations, he decided, that the pulpy substance did 
not consist entirely of vessels, but was an additional and different 
structure. 

He also suggested, that as the brain and muscular fibres were 
so covered by blood-vessels in the injected preparations of 
Ruysch, that they appeared to be composed entirely of vessels, 
when in fact they consisted of a different substance, so the pulpy 
substance of the spleen was covered or obscured by the blood- 
vessels which passed through it, without constituting its whole 
substance. 

He confirms the account of Malpighi respecting the Whitish 
Vesicles or Follicles, and states, that in a majority of cases they 
are not to be discovered without a particular preparation ; but 
that they are generally made obvious by long maceration of the 
spleen in water. In his opinion they are the most essential part 
of the organ. 

Notwithstanding these investigations of M. De La Sone, the 
question respecting the structure of the spleen remains not com- 
pletely decided evert to this day. 

Haller, who was perfectly well acquainted with the subject, 
inclined to the opinion of Ruysch; while Sabatier adopted com- 
pletely the opinion of De La Sone. 

It appears from the statement of Gavard, that Desault did 
not admit the existence of the transparent bodies ; although he 
believed that the pulpy substance of the spleen consisted of 
cells which resembled those of the cavernous bodies of the 
penis. 

Boyer, whose descriptions of the animal structure appear to 
have been formed with scrupulous exactitude, admits the exist- 
ence of transparent bodies; sometimes so small as to be scarce- 
ly visible, and sometimes as large as the head of a pin. He ob- 



108 BRITISH ANATOMISTS ON THE SPLEEN. 

serves, that the best method of examining them is to place a 
very thin slice of the spleen between the eye and a strong light, 
when the transparency of these bodies occasions the slice of the 
spleen to appear as if perforated. 

As to the general structure of the pulpy substance, he avows 
himself unable to decide respecting it; but observes, that upon 
examining the cut surface of the spleen, you perceive black liquid 
blood flow from the vessels; if you then scrape this surface, you 
may express easily a species of sanies different from that which 
flows from the vessels, which, after exposure, becomes red, and 
resembles coagulated blood; whether this is contained in the ca- 
pillary vessels, or in the cavities of this organ, he acknowledges 
himself unable to determine. 

Notwithstanding the sentiments of these French gentlemen, 
many of the British anatomists, who are entitled to great atten- 
tion on account of their skill in minute injections, have adopted 
the ideas of Ruysch. Among these are to be mentioned the late 
Dr. F. Nicholls, and many of the anatomists of London, as well 
as the second Professor Monro, of Edinburgh. There are, how- 
ever, two remarkable exceptions to this account of the British 
anatomists. The late Mr. Falconer, who wrote a dissertation 
on the situation and structure of the spleen, which contains the 
sentiments of the late truly respectable Mr. Hewson,* after stat- 
ing that the organ was extremely vascular, so that when injected 
it appeared like a mere congeries of vessels, makes this unequivo- 
cal assertion — that there are innumerable cells dispersed through- 
out the whole substance of it, which are so small that they are 
only to be discovered by the aid of a microscope ; and are to be 
seen after steeping a thin piece of spleen, the blood-vessels of 
which have been minutely injected in clear water, d urine a 
day, and changing the water frequently. He also adds, that the 
ultimate branches of the arteries and veins form a beautiful net- 
work on each cell; and that these cells are sufficiently distin- 
guished from the irregular interstices of the cellular substance, 
by their round figure and their great regularity. 

* See Experimental Inquiries, vol. iii. 



QUESTIONS RELATING TO THE STRUCTURE OF THE SPLEEN. " jqq 

Sir Everard Home, in his papers on the structure and uses of 
the spleen, confirms the account of the vesicles in this organ ; 
and adds that these vesicles are occasionally seen in a distended 
and in a contracted state. That when distended they are twice 
as large as when contracted, and are distinguishable by the 
naked eye; whereas when contracted, they require a magnify- 
ing glass to be distinctly seen. These observations appear to 
have been made upon quadrupeds.* 

Professor Soemmering appears to unite in the general senti- 
ment of the British anatomists, that the spleen is simply vascular. 
He says, that the tuberculi which sometimes appear in it, when 
examined with a magnifying glass, appear to be composed en- 
tirely of vessels. 

There are, therefore, two questions not perfectly decided re- 
specting the spleen. 

First. Whether its general structure is simply vascular; or 
whether there is any other structure either cellular or more 
substantial, which composes its general bulk. 

Second. Whether the small transparent vesicles, originally 
described by Malpighi, are to be regarded as essential parts of 
the structure of the spleen. 

With respect to the first question, the injections of Ruysch, 
and of the British anatomists in general, and even of Mr. Hew- 
son, as well as of Haller and Soemmering, seem to afford positive 
facts in opposition to those of a negative kind adduced by M. De 
La Sone, and render it highly probable that the general struc- 
ture is simply vascular. 

But the second question stands on different grounds. The ex- 
istence of small transparent vesicles, although denied by Ruysch, 
and neglected by the British anatomists in general, was asserted 
as a positive fact by Malpighi and De La Sone ; and their as- 
sertions have been confirmed, not only by most of the French 
anatomists, but also by Hewson and Home among the British. 

The sentiments of physiologists respecting the functions of the 
spleen, are more discordant than those of anatomists respecting 

* See the London Philosophical Transactions for 1 808. 
VOL. II. 10 



J20 STRUCTURE OF THE SPLEEK. 

its structure ; although the subject has been considered by many 
authors of great ingenuity.*' 

— The spleen is met with only in vertebrate animals, and in 
them its presence is nearly constant. The whitish rounded cor- 
puscles of Malpighi, which are found in many animals and 
occasionally in man, and are visible to the naked eye in the red 
substance of the liver, have been more recently described by 
Dupuytren and Assolant as grayish bodies, without any cavity 
in their interior, one-fifth of a line in diameter, and so soft as to 
take the liquid form when raised on the knife. Meckel considers 
them probably hollow, at all events, very soft and vascular. 
— Miiller considers them as growths or processes connected with 
the sheaths with which the capillary branches of the splenic artery 
are provided. But of their intimate texture nothing is known. 
— The pulpy substance of the spleen consists of a mass of red- 
brown granules, as large as the red particles of the blood, but 
differing from them in form, being very irregularly globular. 
— These granules are easily separable from each other, and in 
their midst the minute arteries ramify in tufts, and terminate in 
the plexus of venous canals, in which all the blood of the spleen 
is poured, before it is carried out of the organ by the splenic vein. 
There are no distinct cells in the spleen ; those spaces seen in 
sections of the organs which have been mistaken for cells, are 
divided venous canals exceedingly thin and delicate. When the 
spleen is inflated with air, these vessels are distended, and assume 
a slightly cellular appearance. 

— The spleen is now generally considered as belonging to the 
class of erectile tissues, and to serve as a diverticulum to the 
blood, which accumulates temporarily in the venous plexuses of 
the stomach during digestion. Its uses in the economy are by 
no means well understood, and in health or disease, seems to 
have but little functional connexion with other organs. In the 
female, it appears to sympathize more with the organs of gen- 
eration than any others. Its extirpation in animals may take 

* See M. Lieutaud, Elementa Pliysiologise ; Hewson's Experimental Inquiries, 
vol. iii. ; Dr. Rush, Medical Museum, vol. iii. ; and Haller, Elementa Physiologic, 
torn. vi. page 414. 



EXTIRPATION OF THE SPLEEN. 



Ill 



place without destroying life. This operation was practised by 
Dr. Schultz,* twenty-seven times in dogs, cats, goats, and rabbits, 
and of which but one died from the operation. When the wound 
had healed, he remarked but little functional disturbance in any 
of the organs of the body except the generative. The chyle 
drawn from the thoracic duct, presented the same appearances 
as that of animals in which the experiment had not been practised ; 
which is counter to the opinion of Tiedemann and Gmelin, who 
affirm the use of the spleen to be that of furnishing through its 
numerous absorbent vessels, a fluid which reddens and assists in 
animalizing the thoracic chyle. 

— In the animals operated upon, the power of procreation was 
greatly impaired, though not entirely destroyed. 

* Hecker's Annalen, torn. xii. 



112 °F THE GLANDULE RENALES. 



CHAPTER IV. 

OF THE URINARY ORGANS AND THE GLANDULiE RENALES. 

The urinary organs consist of the Kidneys, which are situated 
in the lumbar regions ; of the Bladder, which is in the pelvis ; 
of the Ureters, which are flexible tubes or canals that pass from 
the kidneys to the bladder ; and of the Urethra, or tube through 
which the urine is discharged from the bladder. 

These organs have but little connexion with the peritoneum. 
The kidneys are behind it, and a considerable quantity of cellular 
membrane is placed between them and it. The ureters are also 
behind it ; and but a part of the bladder is invested with it. 

The Glandules Renales are described with the urinary organs, 
on account of their contiguity to the kidneys; and to avoid a 
derangement of the natural order of description, they are con- 
sidered first. 

The urethra pertains to the organs of generation as well as to 
the urinary organs, and can be described most advantageously 
w r ith them. 

Of the Glandules Renales. (Renes Succenturiati, Capsulce Atra- 

biliares.) 

These are two small bodies situated on the psoas muscles, one 
on each side of the spine, behind the peritoneum and above the 
kidney, being in contact with its upper and anterior edge. They 
have an irregular semilunar figure with three sides, one of which 
is accommodated to the convexity of the kidney. Their colour 
is commonly a dull yellow. 

The appearance and texture of these bodies have some re- 
semblance to those of glands, and hence their name, but they 
have no excretory duct. 



CAPSULE RENALES. J 13 

When they are laid open by an incision, a cavity often 
appears, which is somewhat triangular, and from the lower part 
of it a small thin ridge arises.* 

A small quantity of fluid is generally found in it, which has a 
very dark colour in adults, is yellowish in young subjects, and 
red in infants. 

These bodies have not a single artery appropriated to them, 
as the spleen has, but receive small branches from several con- 
tiguous sources; namely, from the arteries of the diaphragm, 
from the coeliac artery or the aorta, and from the arteries of the 
kidneys. There is generally one principal vein, as well as some 
that are smaller, belonging to each of these bodies: the large 
vein, on the right side, generally opens into the vena cava ; and, 
on the left, into the left emulgent vein. 

These bodies were first described by Eustachius, and have 
been regarded with attention by many anatomists since that pe- 
riod. They exist in a great number of animals ; but their nature 
and functions are altogether unknown. 

— Rayer,f adopts the opinion of Meckel, that in the normal 
state there is no cavity whatever in the renal capsules. When- 
ever I have observed this cavity in my dissections, it has been 
always filled with dark blood or a yellowish albuminous fluid, 
and the walls of the cavity have presented an irregular appear- 
ance, though having the general triangular form of the gland. 
In the healthy state, the renal vein can be traced into the centre 
of the gland which then presents a spongy appearance. 
— Rayer considers the cavity as always produced by haemorrhage, 
arising from a rupture of some of the lax vessels of the capsule, 
which causes a forcible separation of the soft tissue of the gland. 
He describes several cases of what he calls apoplexy of the gland, 
where a large amount of blood was collected in a cyst formed 
from the gland. Muller believes that the developement of these 
glands is in some measure connected with that of the generative 
organs. — 

* The cavity in these bodies has sometimes been sought for in vain. Ilallcr 
found it in sixteen cases out of nineteen. 
t Sur Les Maladies des Reins. — p. 

10* 



114 THE KIDNEYS AND URETERS. 

Of the Kidneys and Ureters. 

The kidneys are two glandular bodies which secrete the urine. 
They are of a dull red colour, and their form has a strong re- 
semblance to that of the bean which bears their name. They 
have a peculiar texture, which is uniform, and not granulated or 
composed of acini ; and they are covered by a thin delicate 
tunic, which has no connexion with the peritoneum. 

They are situated in the lumbar regions of the abdomen, one 
on each side of the spine. They are opposite to the two last 
dorsal and the two first lumbar vertebras. They rest principally 
upon the psoas and quadratus lumborum muscles, and their position 
is oblique ; the concave edge presenting inwards and forwards, 
the convex edge backwards, and the upper extremity approach- 
ing nearer to the spine than the lower. 

The Right Kidney is situated rather lower than the left : it is 
below the posterior part of the right lobe of the liver, and behind 
the duodenum and the colon. The Left Kidney is below the 
spleen, and behind the descending portion of the colon. Each of 
the kidneys is below and very near to one of the glandulse 
renales. 

They are surrounded with a large quantity of lax adipose 
membrane, which in corpulent persons forms a very large mass 
of adeps around them ; while in the emaciated they are sur- 
rounded with a membrane almost free from fat. Each kidney 
has two broad sides, two extremities, and two edges. The side 
or surface which is posterior, when the kidney is in its natural 
situation, is rather broader than the other. The upper extremi- 
ty, or portion, is also broader and larger than the lower. The 
edge which is posterior and external is regularly convex ; the 
anterior edge is concave ; but the concave edge or margin is 
not very regular. In the middle it is largely indented ; in this 
indentation is a deep fissure, which separates the two broad sur- 
faces or sides of the gland from each other; and here the 
breadth of the posterior surface is evidently greater than the 
anterior. 

Each of the kidneys receives a large artery, which proceeds 



THE KIDNEYS. 215 

immediately from the aorta, nearly in a rectangular direction. 
A vein, which opens into the vena cava, accompanies the artery. 
It is obvious, from the situation of the kidneys with respect to 
the great vessels, that the artery on the right side must be longer 
than that on the left, and that the reverse of this must be the 
case with the veins ; the veins are also anterior to the arteries. 
At the great fissure these vessels divide into several branches, 
which enter the kidney at that place. The branches of the vein 
are before and above; those of the artery are below, and in the 
middle. Surrounded more or less by the branches of those ves- 
sels, is a membranous sac ; the breadth of which extends from 
above downwards. This sac terminates in a tube that proceeds 
from the lower part of the fissure down to the bladder. The 
sac is denominated the pelvis of the kidney, and the tube a 
ureter : each of these parts will soon be more particularlv de- 
scribed. 

The substance of the kidney, as has been already said, is uni- 
form in its texture, and of a reddish brown colour. When it is 
divided by an incision made lengthways, and from its convex to 
its concave edge, there appears to be a small difference in the 
different parts of it. The exterior part, which is called cortical, 
is rather more pale in colour and softer in consistence than the 
internal part. It varies in thickness, so that some writers have 
described it as equal to two lines, and others to one-third of the 
kidney. In a majority of subjects it will be found between the 
two statements. 

The interior part is called medullary, or tubular, and appears 
to be composed of very fine tubes. These tubes are so arranged, 
that a number of papillae or cones are formed by their converg- 
ence, and project into the fissure of the kidney. These papilla? 
have been supposed to consist of a substance different from either 
of the two above mentioned, but they appear to be formed mere- 
ly by the tubular part. 

The arteries, accompanied by corresponding veins, and by 
nerves and absorbent vessels, after ramifying in the fissure of the 
kidney, proceed into its substance, and continue their arborescent 
ramifications until they have arrived very near the exterior sur- 



jig THE KIDNEYS. 

face. They are so uniformly distributed to the different parts of 
the organ, that when the blood-vessels are injected with wax, 
and the substance of the kidney is removed from the injected 
matter, as is the case in corroded preparations, the injection ex- 
hibits accurately the form of the kidney. 

The large branches of the blood-vessels occupy the vacuities 
between the papillae in the fissure of the kidney. When they 
penetrate the substance of the kidney, they are enclosed by 
sheaths which are derived from the coat of the gland, and are 
surrounded by membrane which frequently contains adeps. 

There are commonly ten or twelve papillae in the fissure of 
each kidney, but there are sometimes more and sometimes less 
than this number. These papillae are surrounded by a mem- 
branous sac of a corresponding form ; the papillae being a cone, 
and the sac resembling the upper part of a funnel. The sac is 
therefore called an infundibulum, or calyx. Sometimes there 
are two papillae in each infundibulum, and then the form of the 
sac is not so regular. The infundibulum adheres to the base of 
the papillae, but lies loose about the other parts of it. Each in- 
fundibulum communicates at its apex with the pelvis of the 
kidney. 

The Pelvis, as has been already mentioned, is a membranous 
sac which terminates in the ureter, exterior to the kidney. This 
sac generally divides itself, in the fissure of the kidney, into three 
large irregular branches, called calices, each of which very soon 
terminates in three or four of the infundibula above described. 
That portion of the sac which terminates in the ureter is exterior 
to the kidney. 

When the interior parts of the kidney are exposed to view, by 
the section above mentioned, after the arteries and veins have 
been minutely injected, the cortical part will be found to consist 
almost entirely of the minute ramifications of these vessels. 
Among them are some small bodies, which are dispersed through 
the substance, like berries on a bush : these are asserted also to 
be composed of vessels. 

The tubular part certainly proceeds from this vascular corti- 



CORTICAL AND TUBULAR TORTIOXS OF THE KIDNEY. 1 i 7 

cal substance: for Ruysch, and after him several other injectors, 
have filled these tubes with injections thrown into the arteries. 

The tubuli, of which this part is composed, seem to arise ob- 
scurely from the cortical part. They soon assume somewhat of 
a radiated direction, and are finally arranged so as to form the 
papillae or cones above described. 

On these papillae or cones some of them can be traced, unit- 
ing with each other, to form larger tubes, which terminate on 
the surfaces of the papillae, in orifices large enough to be seen 
distinctly. From these orifices urine may be forced out by com- 
pressing the papillae. On this account the tubes have been called 
tubuli uriniferi. 

— The minute round bodies which are distributed among the 
arteries and veins of the cortical portion, and are visible to the 
naked eye, are called the corpuscles of Malpighi. These bodies, 
Malpighi and Schumlansky, believed to be hollow sacs, with 
vessels ramifying on the parietes, and which secreted the urine. 
Ruysch, Hewson, and more recently Huschke, and Miiller, have 
shown that they are formed entirely of an agglomeration of mi- 
nute vascular branches, and are mere reservoirs'of blood. 
— The conoidal, medullary or tubular portions of the kidney, are 
from twelve to eighteen in number. The bases of these are 
rounded, and turned to the cortical matter which covers them, to 
the thickness of two lines, and dips in for a much greater depth 
between their rounded margins. The arteries and veins send up 
their ramifications to the cortical matter, between these different 
conoidal bodies so as to separate them from each other. The 
conoidal bodies terminate in the infundibuli, in little nipple-like 
projections, called papillce renales. At the apex of these, there 
is usually a depression, called foveala. There are usually but 
ten or twelve of these papillae, two of the conoidal bodies ter- 
minating in several places in a common papilla. The conoidal 
bodies being pyramidal in their shape, are sometimes called the 
pyramids of Malpighi. 

— Each of these conoidal bodies or pyramids, is composed of 
an immense number of minute tubes, (tubuli uriniferi,) which 



JJg DUCTS OF FERREIN.— DUCTS OF BELLINI. 

terminate by a small number of orifices on the surface of its 
papilla. 

— These tubes originate in the cortical portion, in their course 
through which they are serpentine and tortuous, and are called 
the ducts of Ferrein (ducti Ferreinei;) the same ducts, as they 
pass from the cortical matter to the papilla become straight, and 
are called the ducts of Bellini, from two anatomists who devoted 
much attention to the structure of the kidney. Ferrein ascer- 
tained that the general convergence of each cone or pyramid of 
Malpighi, from its base to its papilla, was caused by the union of 
many of the ducts together, into common tubes, so as to constitute 
lesser pyramids, called the pyramids of Ferrein, (Pyramides Fer- 
reinei.) The ducts of each of these pyramids, subsequently unite 
together, so that the convergence is uniform down to the papilla, 
where for the whole, there appears to be but from twenty to thirty 
terminal orifices. In each conoidal body, the pyramids of Ferrein, 
are said by that anatomist to be seven hundred in number, which, 
as the number of cones in a kidney are upon an average about 
fifteen, would make the whole number of pyramids in the kid- 
ney, ten thousand five hundred. 

— Again, each of the pyramids of Ferrein, is said at its base to 
be composed of many hundred separate tubes, each of wjiich 
tubes, according to Eysenhardt, is composed of twenty smaller 
ones : but the observations of this latter writer, even by the Ger- 
man anatomists, are considered rather as an exaggeration. 
— The exact mode of origin of the tubuli uriniferi has been long 
a question of doubt. According to Krause and Miiller, who have 
recently investigated this subject, they originate as closed tubes, like 
the ducts of other glands. These ducts, when examined with the 
microscope in the cortical portion, appeared two or three times 
less in diameter, than the tubuli seminiferi, and therefore invisible 
to the naked eye, though they were still much larger than the 
capillary blood-vessels, which form in the cortical structure of 
the kidneys a very minute net-work. These ducts of the corti- 
cal portion (ducti Ferreinei,) anastomose frequently with one an- 
other ; they are fiexuous and closely aggregated together, which 
gives to the cortical matter the appearance of a solid mass. 



STRUCTURE OF THE KIDNEY. j jg 

— From the minute currents of blood with which these vessels 
supply the walls of the ducts, the secretion of urine, according 
to Miiller, takes place ; a part of the contents of the blood-ves- 
sels permeating the walls of the ducts, and undergoing in the 
transit probably some change. It is certain, however, that there is 
some intimate communication between the origin of the ducts, 
and the radicles of the veins, even in man and the higher ani- 
mals. In oviparous animals, as has before been observed, the 
secretion of urine takes place from a portal vein. 
— A fine injecting fluid will pass readily from the veins into the 
uriniferous tubes ; and I find no difficulty in passing air in the 
retrograde direction, from the ureter into the veins by inflation 
of the former with a large blow-pipe ; the cut extremity of the 
veins being retained under water, large bubbles of air will be 
seen to escape from it during inflation. M. Huschke,* was also 
very successful in passing coloured fluids in the same direction, by 
the aid of the air-pump. The uriniferous tubes were always well 
injected, the fluid passing in by the orifices on the papilla;; and in 
most cases the venous plexus in the cortical structure, was also 
filled. But in no instance, in man or the inferior animals, did he 
find the fluid passing into the corpuscles of Malpighi, or into the 
arteries. 

— The average weight of a healthy kidney is from four to five 
ounces. In the nephritis albuminosa, granular disease of Bright. 
which is an affection of the cortical or glandular substance only, 
attended with albuminous urine, the first developement of the 
minute red points, which subsequently become the granulations 
of Bright, correspond for the most part according to Rayer,f to 
the highly vascular corpuscles of Malpighi. — 

In the fcetal state the kidney is formed of a number of distinct 
lobuli, each of which consists of a papilla with the cortical mat- 
ter connected to its base. Soon after birth these lobuli coalesce; 
and in two or three years the substance of the kidney appears 
uniform, as above described. In some animals this lobulated 
structure continues during life: in them, and also in the foetus, 
each lobe appears like a distinct organ. Although in the adult 
kidney this structure has disappeared, the papillae and the tubular 
* Isis, torn. xxi. t Opcr. citat. 



120 



NERVES AND LYMPHATtCS.-COAT OF THE KIDNEY. 



part connected with them are somewhat detached from each 
other, in a manner corresponding to their original arrangement. 

— In the foetus the renal capsule appears very large, when com- 
pared with the kidney itself; which seems to indicate, that that 
organ performs some office of much importance in the foetal 
economy. — 

The Nerves of the Kidneys originate from the semilunar gan- 
glion, formerly mentioned. They form a plexus round the blood- 
vessels, and go with them into the gland. 

The kidneys have internal Fig. 58.* 

and external absorbent vessels, 
although the external vessels 
are very small. These absor- 
bents pass through glands in 
the lumbar region to the tho- 
racic duct. 

The proper coat of the kid- 
ney is said, by some anato- 
mists, to consist of two lamina; 
but this cannot be shown in 
common cases. It appears 
simple in its structure, and 
very flexible. It is but slight- 
ly connected to the glandular 
substance which it encloses, 
and may be easily peeled off. 
It is reflected inwards at the 
fissure of the kidney, and can 

be traced inwardly to some distance, forming sheaths for the 
vessels. In this internal situation it is very thin. 

* Fig. 58 is a vertical section of a kidney, in which the ureter is seen entering 
the organ, and dilating into a large sac called the pelvis. The pelvis is divided 
into four calices, of which three are seen in part, in this section ; each calix is 
subdivided into four infundibuli, of which, of course part only can be seen in this 
semi-section of the organ. The striated conoidal bodies are seen terminating by 
their papillae in these infundibuli ; and in one infundibulum a papilla is seen per- 
forated by foramina, which are the terminal orifices of the uriniferous tubes. Be- 
tween the rounded bases of the conoidal bodies, and on the periphery of the kidney 
is seen the cortical substance. — r. 




STRUCTURE OP THE URETERS. 



The Ureters. 



121 



The pelvis of the kidney terminates exteriorly in the Ureter, 
which is a membranous cylindrical tube, rather flattened, and 
between three and five lines in diameter, with some variations 
in this respect. 

The Ureters descend from the pelvis of the kidney so as to 
pass obliquely across the psoas muscle and the great iliac vessels. 
They are behind the peritoneum, but in contact with it. They 
approach the pelvis near the junction of the os ilium with the 
sacrum, and thence descend forwards and inwards, surrounded 
with loose cellular membrane, to the lower part of the bladder 
into which they are inserted at its external and posterior part. 
They first penetrate obliquely the muscular coat, and then pro- 
ceed between the muscular and internal coats from half an inch 
to an inch, in an oblique direction, from without inwards and 
forwards, when they terminate by small orifices in the internal 
coat, each of which is at an equal distance, (rather more than 
an inch,) from the orifice of the urethra, thus forming a triangle 
with it. 

The ureters are said to have three coats. The exterior appears 
to be derived from the cellular substance; within it is another, 
which has been regarded very differently by different ana- 
tomists; some considering it as merely membranous, and others 
as muscular. If the ureter be laid open and the internal coat 
peeled off", the muscular structure of this coat is often very per- 
ceptible. 

The internal coat is called villous, or mucous, and is continued 
from the internal coat of the bladder. Over this coat mucus is 
constantly spread, which defends it from the acrimony of the 
urine. It is very difficult to separate the two last mentioned 
coats from each other. 

The ureters receive blood-vessels and nerves from those of the 
neighbouring parts. Their internal coat is very vascular, and is 
also very sensible of irritation. The passage of a small urinary 
calculus can be traced from the pelvis of the kidney to the 

VOL. II. 11 



|22 OF THE URINARY BLADDER. 

bladder, by the exquisite pain and the spasmodic affections which 
it often excites. 

Of the Urinary Bladder. 

The urinary bladder is a large sac, of a muscular and mem- 
branous structure, which occupies the anterior part of the cavity 
of the pelvis, immediately within the ossa pubis. 

The size of the bladder is in a continued state of variation, 
according to the quantity of urine secreted. When moderately 
distended, it is of an irregular oval form, but rather more flat at 
its lower extremity than above. It varies in form according to 
the different circumstances of the pelvis to which it has been 
subjected. 

It is fixed firmly and immovably to the pelvis immediately 
within the symphysis pubis; so that it is always to be found there 
of a larger or smaller size. This fixture is produced by the at- 
tachment of the lower portion of fundus of the bladder to the 
parts beneath it, but principally by the anterior ligaments of the 
bladder which proceed one on each side from the lateral surfaces 
of the prostate gland, and are inserted into the pubis of the 
corresponding side at the lower part of the symphysis. These 
ligaments are in fact the extension of a membrane, (called by 
the French anatomists, the pelvic aponeurosis,) which proceeds 
from the upper part of the pelvis to the side of the prostate 
gland and bladder, and which may be seen by turning off the 
peritoneum from the levator ani muscle.* It is sometimes com- 
pletely empty, and occupies no more space than the thickness of 
its coats requires. When moderately distended, it occupies a 
considerable portion of the pelvis : when distention increases, it 
presses the parts posterior to it against the sacrum, and extends 
itself above the brim of the pelvis into the general cavity, rising 
not only to the umbilicus, but in some cases to the epigastric 
region. 

In males the relative situation of the bladder and rectum is 

* See Thesis on Femoral Hernia, &c, by Gilbert Breschet. Paris, April, 1819. 
Colles' Surgical Anatomy, Dublin, 1811, for a more minute account of this mem- 
brane. — H. 



OF THE URINARY BLADDER. J23 

such, that the upper and middle part of the rectum is behind the 
bladder; but the lower part of the rectum, following the curve 
of the os sacrum and coccygis, is below the posterior part of the 
bladder. 

In females the vagina and uterus are situated between the 
bladder and rectum ; so that the connexion of these last men- 
tioned parts is very different in the two sexes. 

The peritoneum is reflected at the anterior part of the brim of 
the pelvis from the abdominal muscles, which it lines, to the upper 
part of the bladder, which is generally contiguous to the brim of 
the pelvis. It continues over to the posterior side of the bladder, 
and passes down upon it some distance towards the lower part : 
but before it has arrived at the bottom, it is reflected towards 
the sacrum. 

In males it extends from the bladder to the rectum, and in 
females, to the vagina and uterus; so that there is a considerable 
portion of the lower part of the bladder which is not invested 
by the peritoneum. It also follows, that when the bladder is 
extended into the abdomen, and rises above the brim of the 
pelvis, that part of it which presents anteriorly, and is in contact 
with the abdominal muscles, is without a covering of peritoneum : 
being below it. 

— It is usual for anatomists and pathologists to divide the 
bladder when moderately distended into four regions, for the 
purposes of description, viz. The middle part or body, the top or 
upper fundus, the inferior part or lower fundus, and the neck, 
at which the urethra commences. 

— In the foetus and young child, the neck of the bladder is the 
most depending portion. In the adult, the bottom of the bladder 
is depressed and expanded, so as to form a pouch below the 
level of the neck, which is technically known as the bas fond. 
In this part the urine first begins to accumulate when the organ 
has been emptied, and calculi usually lodge. 
— The diameter of the bas fond is rather greater laterally than 
in the antero-posterior direction. Its lateral portions in both 
sexes are in contact with the levator ani muscles, and correspond 
to the spaces between the anus and the tuberosities of the ischium. 



124 MUSCULAR COAT OF THE BLADDER. 

In the female, its middle portion is in contact with the walls of 
the vagina; in the male with the rectum in the middle line, and 
with the vesiculae seminales and the vasa deferentia upon the 
side. — 

The bladder is composed of a coat consisting of muscular 
fibres, of a stratum of cellular substance immediately within this, 
and of an internal lining membrane, which has been called vil- 
lous ; but, as there are no villi perceptible on it, it may be more 
properly denominated mucous. 

It should be observed, that, in addition to these coats, the 
bladder has a peculiar investment of the peritoneum, as has been 
already described ; and also of the common cellular membrane, 
which is placed between it in every part to which it is contiguous. 

The Muscular Coat of the Bladder consists of fibres which 
are not spread over it of a uniform thickness, but are thin in 
some places, and in others are collected in fasciculi. They run 
in every direction: some appear longitudinal, others circular, 
and some oblique; and there are interstices between them which 
are occupied by cellular membrane. The longitudinal fibres 
originate from the lower part of the bladder ; and as this is the 
fixed part of that viscus, it is the place from which these fibres 
must necessarily act. These fibres are generally exterior. There 
is no arrangement of the muscular fibres to which the term of 
sphincter can properly be applied ; but many anatomists have 
thought that the fibres near the neck of the bladder, by their 
separate contraction, might prevent the escape of urine ; this 
sentiment, however, is contrary to that of several very respecta- 
ble writers. 

The direction of the fibres, taken collectively, is such that, 
when they all contract, the cavity of the bladder is completely 
obliterated. 

— The longitudinal fibres form the detrusor urince muscle of 
some anatomists. Some of these fibres may be traced by very 
careful dissection, to an insertion in the back part of the prostate 
gland; others into the fasciae covering the surface of the gland; 
and a small delicate band of fibres, according to Harrison, enters 
the notch at the base of the gland, into which it is sometimes in- 



SPHINCTER MUSCLE. 125 

serted, but can frequently be traced forward between the mucous 
membrane and the gland, in front of which it is inserted by a deli- 
cate tendon, at the lower part of the seminal caruncle or caput galli- 
naginis. The office of this strip of fibres, is, he thinks, to depress 
the uvula, and thus open the neck of the bladder, and to draw r 
down the seminal caruncle, (which he considers a vascular erectile 
body like the glans penis,) into the cavity which surrounds it, 
called sinus pocularis, out of the way of being irritated by the 
urine. The fibres which cover the prostate gland, connect it 
with the bladder in urination, and probably force out its mucus 
to lubrify the passages. 

— There has been much contrariety of opinion among anatomists 
of reputation, in regard to the existence of a sphincter muscle at 
the neck of the bladder, arising from the colourless appearance 
and reticulated character of the fibres of the part. 
— Those who deny the existence of a sphincter, as Bichat, Cloquet, 
Marjolin, consider the neck of the bladder made up of elastic 
fibro-ligamentous tissue, continuous with the longitudinal fibres, 
and which expands under the action of the detrusor muscle, to 
give passage to the urine. Those who admit the existence of a 
sphincter, as C. Bell, Meckel, Horner, Harrison, etc., describe it, 
however, very differently. 

— The inferences drawn from diseased conditions of the organ, 
are evidently much in favour of the existence of a muscular 
sphincter ; viz. the paralysis and incontinence of urine, resulting 
from affection of the brain or spinal marrow, and the spasmodic 
closures of the neck in strangury, resulting from neighbouring 
disease, or the acrimonious qualities of the urine. 
— Harrison,* who has investigated it most recently, thus de- 
scribes it : — " When the several strata of longitudinal fibres have 
been raised from the front and lateral parts of this region, the 
circular fibres of the bladder become distinct, but do not appear 
so proportionably increased as were the longitudinal ; but on 
detaching more completely the longitudinal strata, down to the 
circumference of the very opening of the urethra, a distinctly 

* Vide article Bladder, by J. Harrison, Cyclop, of Anat. and Physiology, — p. 

11 * 



126 CELLULAR OR NERVOUS COAT. 

fibrous, thai is, muscular tissue is evident, bounding this opening 
laterally and superiorly, but not below. This muscular fasciculus 
is not intimately connected to the general circular coat ; it ap- 
pears redder and of a closer texture, and will be found to be 
attached to the fibrous or tendinous substance, forming the ante- 
rior part of the trigone on each side of the uvula, behind which 
it does not pass. The longitudinal fibres are inserted partly into 
this semicircular muscle, much in the same manner as the leva- 
tores ani are inserted into the circumference of the anus. This 
structure we consider to be partly elastic but essentially muscular ; 
it bounds the urethral opening laterally and above, but not below; 
the slight projection of ihe uvula in the latter situation, and the 
elasticity and gentle state of contraction natural to all the 
sphincter muscles, will preserve this opening in a constantly closed 
state during the quiescent and normal condition of the parts." 
— For a description of the muscles of this part somewhat ana- 
logous to the above, see Dr. Horner's Anatomy, vol. ii. p. 80, 
4th edit. — 

The cellular substance between the muscular and internal 
coats is dense. It yields in a remarkable manner to distention, 
and recovers its original dimensions very easily. From its ana- 
logy to a similar coat in the intestines, it is called the Nervous 
Coat. 

The Internal Coat of the bladder is of a light colour in the 
dead subject, when it has been free from disease. It has been 
called villous improperly; for the villous structure is not apparent 
upon its surface. Being continued from the integuments of the 
body which are extended along the urethra, it has been inferred, 
that the surface of this coat was formed by the epidermis ; and 
some respectable authors have supposed that they had seen cases 
in which portions of the epidermis of the bladder had separated 
and been discharged ; but these appearances are very equivocal, 
and it is by no means certain that an epidermis exists there.* 

The fasciculi of fibres of the muscular coat occasion this coat 

* In the fauces and the follicles of the tonsils, an effusion of coagulable matter, 
in consequence of inflammation, often forms crusts that may be mistaken for 
sloughs of the integuments, although these integuments remain entire. 



INTERNAL OR MUCOUS COAT OF THE BLADDER. J27 

to appear very irregular, but these irregularities correspond ex- 
actly with the arrangement of the fibres of the muscular coat. 

When the internal coat is separated by dissection from the 
muscular, its surface is very smooth and uniform. In the recent 
subject, when no disease has previously existed, it is always 
spread over with mucus of a light colour, but nearly transparent, 
which can be easily scraped off. This mucus is spread upon 
the surface so uniformly, that it must be derived from sources 
which are situated upon every part of the surface ; but these 
sources are not very obvious. On the membrane of the nose the 
orifices of many mucous ducts are very visible, but such orifices 
are not to be seen on this surface. — Haller mentions that he has 
seen mucous glands near the neck of the bladder ; and it is 
stated by the pupils of Desault, that, in one of his courses, he 
pointed out a number of these glands, in a subject who had been 
afflicted with a catarrhal affection of the bladder. 

Notwithstanding that the sources of this mucus are obscure, 
the quantity of it is sometimes immense. In some cases, where 
the secretion is increased by the irritation of a calculus in the 
bladder, the urine is rendered somewhat viscid and white- 
coloured by the mucus mixed with it ; which, after the urine 
has been allowed to remain for some time, subsides in such quan- 
tities as demonstrates that many ounces must be secreted in the 
course of the twenty-four hours. The same circumstances occur 
without the irritation of calculus, in the disease called catarrhus 
vesicEe.* 

It is probable that, in healthy persons, a great deal of it passes 
off unperceived, being dissolved or diffused in the urine. From 
the quantity and the regular diffusion of this mucus on the sur- 
face of the bladder, there is the greatest reason for believing 
that it is effused from every part of the surface ; and it is a ques- 
tion that has not been decided whether it is discharged from 
glandular ducts too small to be perceived, or from the exhalent 

* In some cases this mucus soon becomes putrid, and during the putrefactive 
process deposits a substance which appears to be calcareous. 



128 ORIFICE OF THE URETHRA. 

extremities of the blood-vessels. It is probable that the use of it 
is to defend the internal coat of the bladder from the acrimony 
of the urine. 

The symptoms of a stone in the bladder, as well as of several 
other diseases, evince that this coat is endued with a great degree 
of sensibility. 

It is evident that the essential parts in the general structure of 
the bladder are the muscular coat and the internal coat last de- 
scribed : but in addition to this account of them, there are some 
other important circumstances to be noted in the description of 
this organ. It has been alreadv stated, that the form of the 
bladder was an irregular oval, although it was somewhat varied 
in different persons.* The oval form is not much altered at the 
part called the neck of the bladder, where the urethra passes off 
from it. The orifice of the urethra is situated anteriorly at the 
lowermost part of the bladder. On the lower surface of the 
urethra, at its commencement, and on the bottom of the blad- 
der, immediately connected with the urethra, is situated the 
Prostate Gland, (to be hereafter described with the organs 
of generation,) which is a firm body, that adheres strongly 
both to the bladder and urethra. This circumstance gives 
particular firmness and solidity to that part of the bladder. 
It has also been observed, that the bladder is attached firmly 
to the ossa pubis, at its neck, about the origin of the Ure- 
thra. Each of these circumstances has an effect upon the 
orifice of the urethra ; and when the bladder is opened, and this 
orifice is examined from within, it appears to be kept open by the 
connexion of the bladder with the prostate, and has been very 
justly compared to the opening of the neck of a bottle into the 
great cavity of that vessel.f 

* In the female, the vertical diameter of the bladder is less than in the male. 
Its transverse diameter is greater in consequence of the greater width of the pel- 
vis in the female. — p. 

t The late M. Lieutaud, and after him the French anatomists of the present 
day, have described a small tubercle at the lower and posterior part of the orifice 
of the urethra, which resembles the uvula in form. It has not been noticed here; 
and M. Boyer states, that it is often scarcely perceptible. He, however, makes a 



LIGAMENTS AND VESSELS OF THE BLADDER. 



129 



The orifices of the two ureters are at equal distances from the 
orifices of the urethra, and form with it the angles of a triangle. 
That part of the internal surface of the bladder which is within 
this triangular space, is more smooth than the remainder of the 
same surface, probably in consequence of the adhesion of the 
bladder to the prostate, and to other parts exterior to it. 

That part of the bottom of the bladder, which is immediately 
behind the triangular space, is rather lower than this space; and 
but a small portion of cellular membrane exists between it and 
the rectum in males, and the vagina in females. 

The upper part of the bladder is connected with the umbilicus 
by means of a ligament, which passes between the peritoneum 
and the abdominal muscles. This ligament consists of three 
cords. One of these, which is in the middle, arises from the 
coats of the bladder, and was, in the foetus, the duct called ura- 
chus ; and the other two, which are connected to the bladder, 
principally by cellular membrane, were originally the umbilical 
arteries.* The middle cord is of a light colour and fibrous 
structure; it is thickest at the bladder, and gradually diminishes 
as it approaches the umbilicus. In a few instances it has been 
found to be hollow. In its progress to the umbilicus it becomes 
more or less blended with the linea alba or the tendons of the 
abdominal muscles. The other cords are generally solid. After 
passing from the umbilicus to the bladder they continue on the 
sides of that viscus, and finally terminate at the hypogastric or 
internal iliac artery. 

In the very young subject these cords are invested by distinct 
processes of the peritoneum, but their position is exterior to the 
peritoneum. 

As the bladder is situated very near most of the large rami- 
fications of the hypogastric artery in the pelvis, it receives 

remark which is very worthy of attention, namely, that it is very subject to en- 
largement in old people, forming a tumour which impedes the discharge of urine. 
Sabatier has also made the same observation. 

* See the accounts of these parts in the description of the Abdomen of the 
Foetus. 



130 GENERAL OBSERVATIONS. 

branches from several of them ; viz. from the umbilical arteries 
before they terminate ; from the pubic ; from the obturators, &c. 
These branches ramify in the cellular membrane exterior to the 
muscular coat, and also in the cellular substance between the 
muscular and internal coats. It has been conjectured, that their 
termination in exhalents on the surface of the bladder are re- 
markably numerous. 

The veins correspond with the arteries ; but they are very nu- 
merous on the lower and lateral parts of the bladder, and by 
uniting with the veins of the rectum form a remarkable plexus. 

The Lymphatic Vessels of this organ do not appear more nu- 
merous than those of other parts. They pass on each side of 
the bladder in the course of its blood vessels, and unite with the 
larger lymphatics, and the glands which lie upon the great blood- 
vessels on the sides of the pelvis. 

The Nerves of the bladder are derived both from the intercos- 
tal nerve and from the nerves of the medulla spinalis, which 
pass off through the sacrum; and therefore the bladder is more 
affected than the viscera of the abdomen, by injuries of the me- 
dulla spinalis. 

The action of the muscular fibres of the bladder in expelling urine, and the 
effect of those fibres which are situated near the orifice of the urethra in 
retaining it, can be considered with more advantage after the structure of 
the urethra and the muscles connected with that canal have been de- 
scribed. 

It has been stated that the internal coat of the bladder is very sensible ; but 
it may be added, that in consequence of disease about the neck of the 
bladder, the natural sensibility appears most inordinately increased. 
When the intensity of pain which accompanies these complaints, the fre- 
quent recurrence of paroxysms, and their duration, are taken into view, 
there seems reason to believe that none of the painful affections of the 
human race exceed those which arise from certain diseases of the bladder. 
Happily these diseases are not very common. 

The functions of the kidneys is to secrete urine, and that of the bladder to 
retain it, until the proper time for evacuation. 

The urine may be regarded as an excrementitious fluid, which contains 
many substances in solution that are constantly found in it, and many 
others that are occasionally in it, which are taken as aliment or medicine, 



GENERAL OBSERVATIONS. jgj 

and pass to the bladder with little, if any change. The odour of the rose- 
leaf, the colour of rhubarb, &c. are occasionally perceived in urine. 
The substances constantly found in urine are numerous. The chemical ac- 
count of the subject is so long that it cannot be detailed here ; but the stu- 
dent ought to make himself acquainted with it, and he will read with 
great advantage Johnson's History of Animal Chemistry, vol. ii. page 363 ; 
and also Thomson's Elements of Chemistry, page 833. 



132 MALE ORGANS OF GENERATION. 



CHAPTER V. 

OF THE MALE ORGANS OF GENERATION. 

These organs consist first of the Testicles, and their appen- 
dages. 

2d. Of certain parts denominated the Vesiculce Seminales and 
the Prostate Gland, which are situated near the commencement 
of the urethra, and are subservient to the purposes of generation. 

3d. Of the Penis. 

Of the Testicles and their Appendages. 

The Testicles are two bodies of a flattened oval form. Each 
of them has a protuberance on its upper and posterior part called 
Epididymis, and is connected to parts within the cavity of the 
abdomen by a thick cord, which proceeds through the abdomi- 
nal ring. Each testicle also appears to be contained in a sac, 
which is suspended by this cord and covered by the common 
integuments. 

— The testicle of the right side is usually suspended a little 
higher and is frequently larger than that of the left. They attain 
their fullest developement in middle life, when they are an inch 
and a half long, an inch wide and three quarters of an inch in 
thickness. In old age they are shrunken in size, from the fluids 
being attracted to it in less quantity in consequence of the im- 
paired sensibility of the organ. The upper extremity of each 
testicle has a slight inclination forwards, which is greatly in- 
creased in preparing it for demonstration by breaking up its pos- 
terior attachments. 

— The coverings of the testicles are formed from without inwards, 
of five tunics. 1. The Scrotum. 2. The dartos muscle. 3. The 



SCROTUM. 



133 



tunica vaginalis communis, so called from its covering in closely 
both the cord and testicle of each side, and sometimes tunica 
elythroidcs, from the cremaster muscles which is spread over it. 
4. Of the tunica serosa or tunica vaginalis testis — and 5. Of the 
tunica albuginea, or proper coat of the testicle. — 

That portion of the common integuments which forms the ex- 
ternal covering of the testicles, is denominated, 

The Scrotum. 

The skin of the scrotum, although it is very often in a state of 
corrugation, has the same structure with that on other parts of 
the body, except that it is rather thinner and more delicate. 
The superior delicacy of this portion of the skin is evinced by 
the great irritation produced by the application of stimulating 
substances, and the desquamation of the cuticle, which seems to 
be the effect of irritation. There are many sebaceous follicles 
in this portion of skin ; and after puberty there are often a few 
long hairs growing out of it, the bulbs of which are often very 
conspicuous. There is a small raised line in the middle of this 
skin, which commences at the root of the penis, and proceeds 
backwards, dividing it into two equal parts: this line is denomi- 
nated Raphe. 

The corrugation which so often takes place in the skin of the 
scrotum, appears to be occasioned by the contraction of certain 
fibres, which are in the cellular substance immediately within it. 
This cellular substance appears to be attached in a particular 
way to the skin ; and it also invests each testicle in such a man- 
ner, that when they are withdrawn, a cavity is left in it. It has 
long been observed, that no adipose matter is found in this cellu- 
lar substance : but it is often distended with water in hydropic 
diseases. As the contraction and corrugation of the scrotum 
has been imputed to this substance, it has been examined with 
particular attention by anatomists, and very different sentiments 
have been entertained respecting it. While some dissectors 
have asserted that muscular fibres could be seen in it, which they 
have denominated the Dartos Muscle ; others have said that this 

VOL. II. 12 



134 THE DARTOS. 

substance was simply cellular, and without any muscular fibres. 
This difference of sentiment may possibly have arisen from the 
different conditions of this part in different subjects; for in some 
cases there are appearances which seem to justify the assertion 
that muscular fibres exist in this structure. 

After the testicles are removed, so as to leave the cellular 
substance, connected with the skin, if the scrotum be inverted, 
and this substance examined in a strong light, many fibres will 
appear superadded to the common cellular structure ; and some- 
times their colour can be distinguished to be red.' It is not as- 
serted that this will be uniformly the case ; but certainly it has 
often been observed in this way. 

The existence of an organ which possesses the power of con- 
traction, within the skin of the scrotum and connected to it, is 
evinced by the corrugation which takes place when the scrotum 
is suddenly exposed to cold, after having been very warm. This 
corrugation occurs in a very sudden and rapid manner, in some 
cases, in which the wounded scrotum is thus exposed for the 
purpose of dressing : for example, upon removing an emollient 
poultice from this part some days after the operation for the cure 
of hydrops testis, by incision, if the air of the chamber be cool, 
a motion of the scrotum will take place, almost equal to the 
peristaltic movements of the intestines. 

The Arteries of the scrotum are derived from two sources. 
One or two small arteries, which arise from the femoral artery, 
between Poupart's ligament and the origin of the profunda, are 
spent upon it. These are called the external pudic arteries. It 
also receives some small branches from the internal pudic artery. 

The Nerves of the scrotum are principally derived from the 
lumbar nerves. 

The Dartos, 

— Considered as a muscle, arises on each side from the rami 
of the pubis and ischium, and passes down to the raphe of the 
scrotum, to which it is closely united. It is there reflected 
up in juxtaposition with its fellow of the opposite side, so as 
to form the septum scroti, and leave a pouch on each side for 



THE SPERMATIC CORD. ]35 

the lodgement of the testicles, cords, and three inner tunics, and 
is finally inserted upon the lower portion of the corpus spongi- 
osum urethral. Meckel has suggested that the tissue of the 
dartos forms the transition between cellular tissue and muscular 
fibre, and that there exists between it and the other muscles of 
the body, the same relation as exists between the muscles of the 
superior and inferior animals; in the latter of which the fibrous 
structure is but feebly developed. 

— The researches of Chaussier, Lobstein, and Breschet, seem to 
indicate that the dartos does not exist in the scrotum, before the 
descent of the testicle, and that it is formed by the expansion of 
the gubernaculum testis. — 

The Spermatic Cord. 

The cord which proceeds to the testicle, through the abdominal 
ring, appears at first view like a bundle of muscular fibres ; but 
it consists of an artery and veins with many lymphatic vessels 
and nerves, and also the excretory duct of the testicle, connected 
to each other by cellular substance, and covered by an expansion 
of muscular fibres, which are derived from the lower edge of the 
internal oblique muscle of the abdomen, and continue from it to 
the upper part of the testicle. These fibres constitute the Cre- 
master Muscle. 

— This cellular substance which encloses both the cord and 
testicle, with the cremaster muscle (elythroid tunic) on its outer 
face, forms the tunica vaginalis communis. It is a thin layer, 
and serves to connect the dartos, to the tunica serosa, within. 
— The cremaster* muscle, is formed by an arched arrangement 
of the fibres of the internal oblique and transversalis muscles of 
the abdomen, according to the observations of J. Cloquet, made 
upon a considerable number of foetuses, before, during, and after 
the descent of the testes. The fibres originally passed from 
Poupart's ligament to the pubis, nearly in a straight direction ; 
the testicle as it descended through its canal to the scrotum, 
pushed these fibres before it and formed them into arches or 

* From yLpt/nam, saspendo. — p. 



136 



CREMASTER. 




loops, which increased gradually in length, partly by distention 
and partly by interstitial growth, # 

as the testicle proceeded in its 
descent. Hence when it is de- 
scribed as a distinct muscle, its 
origin and insertion are the same 
as theLt of the fibres. It arises 
from Poupart's ligament, passes 
down on the outer side of the 
tunica vaginalis communis of 
the cord and testicle, and passes 
up on the inner side to be in- 
serted into the pubis. It gives a 
complete reddish colouring to 
these parts, called tunica ely- 
throida.-\ 

— Its redness disappears in ema- 
ciated or dropsical subjects, and 

in cases of hernia the distention causes it to separate apparently 
into two bundles of fibres, internal and external. 
— Its action is to draw the testicle upwards and support it : it is 
distinct from that of the dartos. 

— Fig. 59, from Sir A. Cooper's work on the testis, is a good 
illustration of its structure. — 

The artery above mentioned is called the Spermatic. It com- 
monly arises from the front of the aorta, very near its fellow, at 
a small distance below the emulgents, and is not much larger 
than a crow's quill. It proceeds downwards behind the peri- 
toneum and before the psoas muscle, and ureter. — While it is 
in contact with the psoas muscle, it joins the ramifications of 

* Fig. 59. a, Rectus abdominis, b, Superficial fascia of the cord, c, Inter- 
nal oblique, d, Tendon of external oblique, e, Descending fibres of internal ob- 
lique, or origin of cremaster muscle from Poupart's ligament. /, Insertion of 
cremaster muscle on the pubis, g, g, Descending and ascending fibres, h, The 
loops which are produced in the cremaster by the descent of the testicle, i, Testis, 
covered by the tunica vaginalis to which is attached, by a sort of insertion, the 
loops of the cremaster. — p. 
t From Eto/7/>ov, a sheath. — p. 



VESSELS AND NERVES OF THE CORD. J 37 

the vein. It afterwards meets the vas deferens, and proceeds 
through the abdominal ring to the back part of the testis. Before 
it arrives at the testis, it divides into several branches, two of 
which generally go to the epididymis, and the others penetrate 
the tunica albuginea on the upper and back of the testicle, and 
ramify very minutely on the fine membranous partitions which 
exist on that body. 

In addition to the spermatic artery, there is a small twig from 
the umbilical branch of the hypogastric, which passes to the 
spermatic cord along the vas deferens. 

The branches of the spermatic vein are much larger than 
those of the artery : several of them proceed from the testicle so 
as to correspond with the arterial branches; and in addition to 
these there are many smaller, which also arise from the testicle 
and epididymis. In their course up the cord they ramify, and 
again unite so as to form a considerable plexus, which is called 
the Corpus Pampiniforme, and constitutes a considerable part of 
the volume of the spermatic cord. 

As they proceed upwards, they unite into a few larger veins ; 
and finally, on the psoas muscle, they generally form one trunk, 
which continues upwards so as to unite with the vena cava on 
the right side, and the emulgent vein on the left. 

Sometimes, but not often, there are several spermatic veins on 
each side. 

The Lymphatic Vessels of the testicle are very numerous, 
considering the size of the organ. Six or eight, and sometimes 
more, large trunks have been injected, running upon the cord, 
and continuing to the glands on the back part of the abdomen. 

The Nerves of the testicle are derived from those which supply 
the viscera of the abdomen, and are to be found in the cord, 
although they can scarcely be traced to the testicle. A small 
plexus, called the spermatic, is formed by fibres from the renal 
plexus, and from the sympathetic nerve. These fibres accom- 
pany the spermatic vessels, and in all probability enter the body 
of the testis and the epididymis. The spermatic cord and cre- 
master muscle receive filaments from the second lumbar nerve. 

In addition to these vessels, the Vas Deferens, which is much 

12* 



j 38 TUNICA VAGINALIS TESTIS. 

firmer than either of them, is always to be distinguished in the 
back part of the cord. 

They are all covered in front and on the sides by the cre- 
master muscle, which passes with them from the lower margin 
of the internal oblique, through the abdominal ring, and continues 
to the upper part of the external coat of the testicle, which is a 
sac apparently containing that organ, and upon this sac it is 
spread out and terminates. 

The Tunica Vaginalis. 

The External Coat of the testicle, which is commonly called 
the Tunica Vaginalis, is a complete sac which encloses the tes- 
ticle as the pericardium encloses the heart. It covers the body 
of the testicle and epididymis, and adheres closely to them. It 
is then reflected from them so as to form a loose sac, {Tunica 
Vaginalis Rejlexa,) which appears to contain them. The cavity 
of the tunica vaginalis commonly extends above the body of the 
testis up the cord, and is oval or pyriform. — This sac is so re- 
flected from the body of the testicle that there is a place on the 
upper and back part of that body, at which the blood-vessels 
enter it, without penetrating the sac. 

It resembles the peritoneum and other serous membranes in 
texture, and is therefore thin and delicate. It always contains a 
quantity of moisture, sufficient to lubricate the surface which it 
forms. 

When the tunica vaginalis is laid open, the testicle appears as 
if it were contained in the posterior part of its cavity. 

The testicles, as has been already stated, are of a flattened 
oval form. Their position is somewhat oblique, so that their 
upper extremities look upwards and forwards, their lower ex- 
tremities downwards and backwards, and their edges present 
forwards and backwards. 

The body of the testicle is very firm, in consequence of its 
enclosure in a very firm coat called Tunica A/bi/ginea. Upon 
the upper and posterior part of it is the protuberant substance, 
called Epididymis, which is less firm, being exterior to the tunica 
albuginea. The blood-vessels of the testicle pass into it on the 
posterior edge, at some distance below the upper end. 



TUNICA ALBUGINEA EPIDIDYMIS. 



139 



The Tunica Albuginea, 

In which the body of the testicle is commonly enclosed, is 
firm and dense; and upon this coat its particular form depends. 
It is of a whitish colour, and has a smooth external surface. It 
is thick as well as strong. The epididymis is exterior to it. It 
is only perforated by the blood-vessels, lymphatics and nerves, 
and by the vasa efferentia, which carry out the secretion of the 
testis. One portion of the tunica vaginalis adheres very closely 
to it, and the other appears to contain it. The portion which 
adheres to it is with difficulty separated, but it is a distinct 
membrane. 

— The tunica albuginea is a fibrous membrane, considerably 
thinner than the sclerotic coat of the eye. It is very strong and 
resisting, and is susceptible of very considerable distention, when 
the dilating cause acts slowly, as in the engorgements of the tes- 
ticles called hernia humoralis. It is also endowed with retrac- 
tile properties, as is seen when the distending cause has ceased 
to act. Its internal surface, which is immediately applied upon 
the substance of the gland, gives origin to a great number of 
flattened filaments or septce, which divide the gland into com- 
partments for the separate lobules, and upon which the blood- 
vessels run, to be distributed in the glandular tissue. These sep- 
ta? are directed to the back part of the organ necessarily, as that 
is the direction in which the efferent ducts of the testis pass, and 
form by their accumulation that thickened, oblong, fibrous mass, 
called the corpus highmorianum. — 

The Epididymis 

Differs in colour from the testicle, being more or less reddish. 
It commences at the upper and anterior extremity of the testicle, 
and passes down the posterior edge to the lower end. 

At the commencement the epididymis is somewhat rounded in 
form, and its upper part, or head, has been called the globus 
major: as it descends it lessens, and about the middle of the tes- 
ticle it is flatfish. 

It is firmly attached to the body of the testicle, at the upper 



140 TUBULI, SEPTA, AND BLOOD VESSELS OF THE TESTICLES. 

end, where the vasa efferentia pass to it ; and it is also attached 
to it below; but at the middle it appears nearly detached from it. 
It has therefore been compared to an arch resting with its two 
extremities on the back of the testis ; it is, however, in contact 
with it at its middle ; but about the middle it only adheres by 
one of its edges to the body of the testis, and generally by its 
internal edge. It has a coat which is less firm than the tunica 
albuginea of the testicle, described on the last page. The tunica 
vaginalis of the testicle is so reflected as to cover a great part of 
the epididymis which is not in contact with the testicle, and also 
those surfaces of the epididymis and testis which are in contact 
with each other and do not adhere. 

The Body of the Testicle. 

When the tunica albuginea is cut through, and the substance 
of the testicle examined, it appears to consist of a soft pulpy 
substance of convoluted threads, of a yellowish brown colour, 
which is divided into separate portions by very delicate septa, 
attached to the internal surface of the tunica albuginea at the 
posterior part of the testicle. After maceration, by using a fine 
needle, to detach them from the cellular substance, these threads 
may be drawn out to a great length. In some animals they are 
larger than in the human species; in them, it is said, they are 
evidently hollow, and that very small blood-vessels appear in 
their coats. When mercury is injected into the vas deferens, or 
excretory duct of the testis, in a retrograde course, it can be per- 
ceived in these ducts in the human subject. 

These delicate septa, or partitions, are united to the internal 
surface of the tunica albuginea at the posterior part of the testi- 
cle, at which place there is a body called Corpus Highmoria- 
num, which has been regarded very differently by different ana- 
tomists. It is a long whitish substance, which extends length- 
wise on the posterior part of the testis; and was supposed by 
Haller to resemble one of the salivary ducts. It is now, how- 
ever, generally agreed to be of a cellular structure, and to con- 
tain and support the ducts which pass from the substance of the 
testicle to the epididymis. 



STRUCTURE OF THE TESTICLE, ETC 241 

The blood-vessels pass into the body of the testicle upon these 
septa, and are continued from them to the filaments or tubes of 
which the body of the testicle consists. As in some animals 
blood-vessels are distinguished on these tubes, there is the great- 
est reason to believe that a direct communication subsists be- 
tween them, without the intervention of any other structure, no 
other structure having been discovered : but at the same time it 
ought to be observed, that these tubes have not yet been injected 
from the blood-vessels. Some ingenious anatomists have injected 
the artery going to the testicle so successfully that the injection 
has passed from it into the veins coming out of the testicle ; but 
it is not now said by any of them, that they have filled the tubes 
in this manner. 

Mercury will pass into these vessels from the excretory duct 
of the testicle ; and by means of an injection in that way, the 
structure of the testicle can be unravelled. 

This structure is as follows : the cavity formed by the tunica 
albuginea is divided into a number of apartments by the very 
thin septa or partitions above mentioned. The filamentary or 
tubular matter which fills each of these chambers, consists of a 
seminiferous duct convoluted so as to form a lobule. Three 
hundred of these, according to Monro, may be counted in each 
testicle : from each one proceeds a number of small tubes or 
vessels, which observe a straight course: they are, therefore, 
called Vasa Recta. These vasa recta unite with each other and 
form a net-work on the back of the testis, within the tunica albu- 
ginea, which is called Rete Testis. From this net-work other 
vessels, from twelve to eighteen in number, denominated Vasa 
Efferentia, proceed through the albuginea to the epididymis. 
These vessels are convoluted in such a manner as to form bundles 
of a conical form, which are called Coni Vasculosi. The num- 
ber of these corresponds with the number of the vasa efferentia, 
and they compose about one-third of the epididymis, viz. all the up- 
per part of it. The single tubes which form each of these cones, 
successively unite into one duct, which is convoluted so as to form 
all the remainder of the epididymis and is turned upwards on the 
back of the testicle; the tube gradually enlarges and is less con- 



142 TUBULI SEMIMFERI. 

voluted, and finally becomes straight : it then takes the name of 
Vas Deferens, and continues on the back of the testicle and at 
the inner side of the epididymis to the spermatic cord.*f 

A small solitary vessel or duct, has been observed by Haller, 
Monro, and several other anatomists, to proceed from the upper 
part of the epididymis: sometimes it unites to the epididymis 
below, and sometimes it proceeds upwards. The nature of this 
vessel has not been ascertained with certainty. 

— Monro and Lauth, have both endeavoured to estimate the 
length of the seminiferous ducts. This, however, could not be 
done directly, in consequence of the fragility of the ducts. Their 
estimate is founded partly on measurement, and partly on calcu- 
lation, and can only be considered an approximation to the truth; 
that of Monro exceeds that of Lauth. According to the former, 
there are three hundred lobules, each one consisting of a single 
seminiferous duct, arranged in the lobules in a series of close 
serpentine doublings, which are held together by some delicate 
cellular tissue. When this cellular tissue is destroyed by macera- 
tion, for a short time, each duct may be drawn out with ease, 
and resembles the unravelled thread of a stocking. The diame- 
ter of each duct is ^th part of an inch, and its length a little 
short of seventeen and a half feet. The aggregate length of 
the whole will be, according to the same writer, about 5208 feet, 
or a little less than a mile. In the rete testis, these ducts anasto- 

* De Graff appears to have been the first anatomist who made much progress 
in the successful investigation of the structure of the testicle ; and Haller ought 
to be mentioned next to him, on account of the plate exhibiting this structure, and 
the explanation of it, which he published in the Philosophical Transactions of 
London, for 1749. This plate has been republished by the second Monro, in the 
Literary and Physical Essays of Edinburgh, and also in his Inaugural Thesis. 
Haller has likewise republished it in his Opera Minora. It represents not only 
the vasa efferentia, and the cones formed by their convolutions, but also the rete 
testis, and the vasa recta. Haller could inject no farther than this ; but Monro 
and Hunter soon after succeeded so as to fill a considerable portion of the body of 
the testicle with mercury, injected by the vas deferens. 

t In Mr. Charles Bell's Anatomical Collection in London, there is a preparation 
by his assistant, Mr. Shaw, in which the tubuli testis are completely injected with 
quicksilver and unravelled. I saw also in Leyden, one nearly as successfully exe. 
cuted by Professor Sandifort. — a. 



VAS DEFERENr 



143 




mose very freely together, for the /Vr 60.* 

purpose, according to Lauth, of more 
highly assimilating the fluid they 
carry, by exposing it to a more ex- 
tensive surface of living tissue. The 
length of each efferent duct, with its 
conus vasculosus, he has found from 
seven to eight feet. The length of the 
convoluted duct forming the remainder of the epididymis, he has 
seen to vary in different individuals, from sixteen to twenty-nine 
feet : Monro estimates it at thirty-one. There are but few in- 
stances, it appears,in which anatomists have succeeded completely 
in filling the tubuli testis with quicksilver, from the vas deferens. 
Hunter is said to have succeeded admirably in a preparation, 
which he sent as a present, to Catherine the second of Russia. 
Success in the preparation of this part, is dependent more upon 
perseverance and good fortune, than anatomical skill. It is use- 
less, however, to make the effort except upon a healthy gland, 
taken from a subject who has died of some wasting disease, in 
which excitement in the organ has so long ceased, as to leave no 
obstructing fluid in the ducts. I have now in my cabinet, a 
preparation, in which J succeeded a few years ago, in filling to 
all appearance the whole of the tubular structure of the testicle. 
— According to Vauquelin, the semen masculinum consists che- 
mically, of water 0.90; animal mucus 0.06; phosphate of lime 
0.03; soda 0.01.— 



The Vas Deferens 

Is a very firm tube, about one line in cfiameter, which is not 
perfectly cylindrical exteriorly, although the cavity formed by it 
is so. This cavity is so small in diameter, that it will only admit 
a fine bristle. The coats of the duct have, of course, a con- 
siderable thickness. The internal coat forms a soft surface, 
analogous to that of the mucous membranes: the external is 

* a, Tubuli seminiferi, greatly magnified, b, Mode of anastomosis of these 
tubes, c, Blood-vessels ramifying on these tubes. — p. 



J44 COURSE OF THE VAS DEFERENS. 

firm, and its texture resembles that of cartilage. Owing to the 
small size of the cavity, the internal coat has not been sepa- 
rated from the external. 

It passes upwards in the posterior part of the spermatic cord, 
and continues with it through the abdominal ring, under and ex- 
terior to the peritoneum ; soon after this it leaves the cord and 
dips down into the cavity of the pelvis, forming a curve on the 
side of the bladder, and proceeding backwards, downwards, and 
inwards. In this course it crosses the ureter, and passes between 
it and the bladder. On the lower part of the bladder the two 
vasa deferentia approach each other so gradually that they ap- 
pear to be nearly parallel. They proceed forward between the 
vesiculse seminales, which are two bodies irregularly convoluted, 
that are placed in a converging position with respect to each 
other, and communicate with the vasa deferentia. The vasa 
deferentia finally terminate almost in contact with each other in 
the posterior part of the prostate where they perforate the ure- 
thra. At the distance of about two inches and a half from their 
termination they enlarge in diameter, and become somewhat con- 
voluted. At the posterior margin of the prostate they come in 
contact with the anterior extremities of the vesiculas seminales, 
and unite with them. After this union they diminish in size, and 
become conical ; and passing a short distance through the sub- 
stance of the prostate, during which they approach each other 
more rapidly, they penetrate the urethra, so as to open in it on 
each side of a small tubercle, called the Caput Gallinaginis, 
soon to be described. 

Of the Vesiculte Seminales and the Prostate Gland. 

The Vesiculce Seminales are two bodies of a whitish colour, 
and irregular form, being broad and flat at their posterior extre- 
mities, and terminating in a point at the other. They are about 
two inches and a half in length, and six or seven lines in diame- 
ter at their widest part. Their surfaces are so convoluted, that 
they have been compared to those of the brain. They are situ- 
ated between the rectum and bladder, and are connected to each 
by cellular membrane. 



VESICULiE SEMINALES. 145 

When the vesiculae seminales are laid open by an incision 
they appear to consist of cells of a considerable size, irregularly 
arranged ; but when they are carefully examined exteriorly, and 
the cellular membrane about them is detached and divided, they 
appear to be formed by a tube of rather more than two lines in 
diameter and four or five inches in length, which terminates, like 
the ca3cum,in a closed extremity. From this tube proceed from 
ten to fifteen short branches, which are closed in the same man- 
ner. All these tubes are convoluted so as to assume the form of 
the vesiculae seminales above described ; and they are fixed in 
this convoluted state by cellular membrane, which firmly con- 
nects their different parts to each other. It is obvious that tubes 
thus convoluted, when cut into will exhibit the appearance of 
cells, as in the present instance. 

This convoluted tube composing the vesiculae seminales, ter- 
minates in a very short duct, which is nearly of the same dia- 
meter with the vas deferens ; this duct joins the vas deferens 
so as to form an acute angle. 

From the union of the vesiculae seminales with the vas defe- 
rens on each side, a canal, which seems to be the continuation 
of the vas deferens, proceeds through part of the prostate to the 
urethra, which it perforates. These canals are from eight to 
twelve lines in length; they are conical in form, their largest 
extremity being equal to the vas deferens at that part. 

If the air or any other fluid be injected through the vas defe- 
rens into the urethra, it will pass at the same time into the vesi- 
culae seminales, and distend them. It has been observed, that a 
fluid passes in this manner much more readily from the vasa de- 
ferent ia into the vesiculae seminales, than it does from these last 
mentioned organs into the duct. 

— The union formed by the short duct of the seminal vesicle 
and vas deferens of each side constitutes the ductus ejaculatorius, 
which is about an inch in length, and runs in close contact and 
parallel with its fellow of the opposite side, between the middle 
and lateral lobes of the prostate, and opens obliquely into the 
urethra by a small oblong orifice in the caput gallinaginis. 
Each ejaculatory duct is a conoidal tube, its apex being at its 

vol. 11. 13 



14(] PROSTATE GLAND. 

orifice in the urethra. Hence fluids pass so readily into the se- 
minal vesicles, when injected along the vasa deferentia. The 
diminution of the duct at its urethral orifice, will also increase 
the force of the jet, by which the fluid of the vesicle is ejected, 
when spasmodically compressed by the levator ani muscle. — 

These organs were generally regarded as reservoirs of semen, 
and analogous to the gall-bladder in their functions, until the 
late Mr. J. Hunter published his opinion that they were not in- 
tended to contain semen, but to secrete a peculiar mucus subser- 
vient to the purposes of generation. 

He states the following facts in support of his opinion. 

A fluid, very different from semen, is found after death in the 
vesiculae seminales. 

In persons who have lost one testicle, a considerable time be- 
fore death, the vesiculae seminales on each side are equally dis- 
tended with this peculiar fluid. In the case of a person who had 
a deficiency of the epididymis on one side, and of the vas defer- 
ens on the other, the vesiculae were filled with a peculiar fluid ! 

The sensation arising from redundance of the secretion of the 
testis, is referred to the testes, and not to the vesiculae seminales. 

In some animals there is no connexion between the vasa de- 
ferentia and the vesiculae seminales. 

See Observations on certain Parts of the Animal Economy, 
by John Hunter. 

The Prostate Gland 

Is situated on the under and posterior part of the neck of the 
bladder, so as to surround the urethra. Its form has some re- 
semblance to that of the chestnut, but it has a notch on the basis 
like that of the figure of the heart on playing cards, and it is 
much larger than the chestnut of this part of America. The 
basis of this body is posterior, and its apex anterior ; its position 
is oblique, between the rectum and the symphysis pubis. Below 
there is in some cases a small furrow, which, in addition to the 
notch above, gives to the gland an appearance of being divided 
into two lobes. By turning away the vesiculae seminales and 



PROSTATE GLAND. 



14? 



vasa deferentia from the under surface of the bladder, we bring 
into view a small tubercle at the upper part of the base of the 
prostate, called by Sir Everard Home the third lobe. When 
diseased it projects into the cavity of the bladder.* 

It adheres to the urethra and neck of the bladder. Its con- 
sistence is very firm and dense, resembling the induration of 
scirrhus rather more than the ordinary texture of glands. 

This gland receives small branches from the neighbouring 
blood-vessels, and has no artery of considerable size exclusively 
appropriated to it. 

As it lies in close contact with the urethra, the ducts which 
pass between it and the urethra are not to be seen separate from 
these bodies: but ducts can be seen in the substance of the gland, 
which perforate the urethra, and open on the sides of the caput 
gallinaginis to the number of five or six on each side. By pres- 
sure a small quantity of a whitish fluid can be forced from these 
orifices, which is rather viscid, and coagulable in alcohol. 

The particular use of this fluid is not known. 



Fig. 61.f 



— Fig. 61, is a magnified represen- 
tation of a section of the prostate 
gland, in order to show its vesi- 
cular structure. 

— From these vesicles or modific 1 
follicles, originate many excretory 
canals, which unite together so as 
to constitute about twelve ducts, 
which open into the urethra by the 
sides of the caput gallinaginis. 
— Loder asserts that there are from thirty-two to forty-four of 
these excretory ducts — but this is probably an error. I have sought 
for these ducts in several cases where they were so much enlarged 
from catarrhal inflammation of the bladder, as to admit the end 
of a small probe, without being able to detect more than the 

* In a healthy state, the third lobe forms but a slight elevation in the cavity of 
the bladder, covered by mucous membrane, called uvula vesicae. — p. 

t Section of the prostate gland magnified. — a, a, the two lobes separated, b, ex- 
cretory ducts. — p. 




148 COWPER'S GLANDS. 

number above mentioned. The whole structure of the prostate 
appears to be that of a compound mucous gland, designed to 
throw a lubrifying mucus in great abundance into the urethra, 
at the spot where the urine first enters it, in its passage out- 
wards. 

—The substance of the prostate, in which these ducts and vesi- 
cles are placed, is not exactly understood. It is of a whitish ap- 
pearance, very dense, distensible and yet easily lacerated. The 
superior face of the prostate, is in contact with the anterior liga- 
ments of the bladder ; its inferior with the rectum to which it 
adheres. It is overlapped by the rectum upon the sides when 
the latter is distended with feculent matter ; laterally it corre- 
sponds to the levator ani muscles; by its base, it corresponds to 
the neck of the bladder; and by its apex or anterior extremity to 
the membranous portion of the urethra. Its distance from the 
skin of the perineum, an inch in front of the anus, varies, accord- 
ing to Dupuytren, from two to three inches and a half, as the 
subject is thin or fat. 

— The prostate belongs to the urethra, and not to the bladder as 
students generally suppose. The urethra passes through it near the 
centre, and that portion of it is called the prostatic portion of the 
urethra. The prostate gland is about twelve lines in length, 
measured in the middle line, and eighteen in breadth. 

Comperes Glands, 

— Or, as they are sometimes called, the little prostate glands, 
are placed immediately behind the bulb of the urethra, be- 
tween the two layers of the triangular ligament, yet to be de- 
scribed. Their ducts are about an inch in length, run under the 
mucous membrane of the urethra, and open obliquely into the 
canal about an inch in advance of the glands. The size of the 
glands is usually about that of a garden pea (see Fig. 62*) ; 
sometimes they are much larger. I have succeeded in two or 



* Fig. 62, is a representation of Cowper's gland, cut open, showing its similarity 
of structure with the prostate gland.— p. 




OF THE PENIS. j^y 

Fig. 62.* three instances in distending them with mer- 
cury from their ducts. Their structure and 
office is the same as that of the prostate, (see 
Fig. 62) ; sometimes they appear entirely defi- 
cient One or more small glands of a similar 
description, have been discovered by Littre in front of those of 
Cowper, called the glands of Littre, near the angle of union of the 
crura penis. They are rarely seen. Cowper's glands are placed 
within the circle formed by the ejaculator seminis muscles, the 
action of which will assist in discharging the mucus they secrete. 
In some of the inferior animals, they are vesicular, and have been 
mistaken for another pair of vesiculce seminales ; in these cases 
however, the parts may always be distinguished from one an- 
other ; the vesiculoe seminales are distended with fluid only at the 
epoch of rut; Cowper's glands are always filled with an opaline 
starch-like mucus. — 

Of the Penis. 

The penis, when detached from the bladder, and the bones, 
to which it is connected, and divested of the skin which covers 
it, is an oblong body, which is rounded at one extremity and bi- 
furcated at the other. 

It is composed of three parts, namely, two oblong bodies, 
called Corpora Cavernosa, which, at their commencement, form 
the bifurcated portions, and then unite to compose the body of 
the organ ; and a third part, of a spongy texture, which is con- 
nected to these bodies where they unite to each other, on the 
under side, and continues attached to them during the whole ex- 
tent of their union, terminating in an expanded head w 7 hich 
covers the anterior extremities of the corpora cavernosa. The 
urethra passes from the neck of the bladder, on the under side 
of the penis, to its anterior extremity, invested by this third 
body, which is therefore called Corpus Spongiosum Urethra. 

The two bifurcated extremities are attached each of them to 
one of the crura of the pubis and ischium ; they unite to form 
the body of the penis immediately anterior to the symphysis pu- 

* a, a, Cowper's gland divided, b, Excretory duct. — p. 
13* 



|50 CORPORA CAVERNOSA PENIS. 

bis, to which the lower part of it is also attached ; so that the 
penis is firmly connected to the middle of the anterior part of 
the pelvis. The urethra proceeds from the neck of the bladder, 
between the crura of the ischium and pubis and the crura of the 
penis, to join the body of the penis, at its commencement, and 
near this place its connexion with the corpus spongiosum begins; 
so that there is a small portion of the urethra between the neck 
of the bladder and the commencement of the corpus spongiosum, 
which is not covered by the corpus spongiosum. This is called 
the membranous part of the urethra. 

The penis therefore consists of two oblong bodies of a cellular 
structure, which originate separately, but unite together to form 
it; and of the urethra, which joins these bodies immediately 
after their union, and is invested by a spongy covering, which 
by its expansion forms the anterior extremity not only of the 
urethra, but of the whole penis. These three bodies, thus ar- 
ranged and connected, are covered by cellular membrane and 
skin in a manner to be hereafter described. 

The Corpora Cavernosa, 

Which compose the body of the penis, are two irregular cylin- 
ders, that are formed by a thick dense elastic membrane, of a 
whitish ligamentous appearance and great firmness. They are 
filled with a substance of a cellular structure, which is occa- 
sionally distended with blood. The crura of these cylindrical 
bodies, which are attached to the crura of the ischium and pubis, 
are small and pointed at the commencement, and are united to 
the periosteum of the bones. In their progress upwards they 
enlarge, and at the symphysis of the pubis they unite so as to 
form an oblong body, which retains the appearance of a union 
of two cylinders applied to each other lengthways ; for above, 
there is a superficial groove passing in that direction, which is 
occupied by a large vein: and below there is a much deeper 
groove, in which the urethra is placed. Between these grooves 
is a septum which divides one side of the penis from the other. 
It appears to proceed from the strong membrane which forms 
the penis, and is composed of bundles of fibres, which pass from 
one groove of the penis to the other, with many intervals be- 



CELLS OF THE CORPORA CAVERNOSA. J5J 

tvveen them, through which blood or injection passes very freely. 
Sometimes these bundles of fibres, with their intervals, are so 
regularly arranged, that they have been compared to the teeth 
of a comb. This septum extends from the union of the two 
crura to their termination. 

— It is called the Septum pectiniforme ; the internal between 
the bundles of dense cellular fibres, become so great and so nu- 
merous in the anterior half, that it ceases to divide the penis 
into two corpora cavernosa. Anatomists now consider the cor- 
pus cavernosum as one body imperfectly divided by the septum. 
It is a distinction, however, without much value. — 

Each of these cylinders is penetrated by the main branch of 
the pudic artery, which is about equal in size to a crow's quill. 
These arteries enter the corpora cavernosa near their union, and 
continue through their whole extent, sending off branches in 
their course; the turgescence and erection of the penis is un- 
questionably produced by the blood which flows through these 
vessels into the penis. 

The interior structure of the penis, when examined in the re- 
cent subject, is of a soft spongy nature, and seems stained with 
blood. If any fluid be injected through the arteries this sub- 
stance appears cellular, and may be completely distended by it. 
When air is injected, and the structure becomes dry, the penis 
may be laid open; the cellular structure then appears as if 
formed by a number of lamina and of filaments, which proceed 
from one part of the internal surface of the penis to another, and 
form irregular cells. It has been compared to the lattice-work 
in the interior of bones; and it is suggested by M. Roux, that 
the fibres of which the structure consists resemble those of the 
strong elastic coat of the penis.* If these cells are filled with 

* Mr. John Hunter says on this subject, " That the cells of the corpora caver- 
nosa are muscular, although no such appearance is to be observed in men : for the 
penis in erection is not at all times equally distended. The penis, in a cold day, 
is not so large in erection as in a warm one : which probably arises from a kind 
of spasm, that could not act if it were not muscular. 

In the horse, the parts composing the cells of the penis appear evidently mus- 
cular to the eye, and in a horse just killed, they contract upon being stimu- 
lated — H. 



|52 URETHRA.-CORPUS SPONGIOSUM.-BULB. 

coloured wax, injected by the artery, and the animal substance 
is then destroyed by placing the preparation in a corroding liquor, 
the wax which remains shows that the membranes forming the 
cells are very thin. 

These cells communicate freely with each other ; and, there- 
fore, if a pipe be passed through the strong coat of the penis, 
the whole of them can be filled from it by the ordinary process 
of injection. 

The Urethra 

Is a membranous canal which extends from the neck of the 
bladder to the orifice at the extremity of the penis ; and for a 
very great part of its length is invested by a spongy structure, 
called the corpus spongiosum urethrse. It proceeds from the 
neck of the bladder along the upper part of the prostate ; from the 
prostate it continues between the crura of the penis until their junc- 
tion: it then occupies the great groove formed by the corpora ca- 
vernosa on the lower side of the penis, and continues to the orifice 
above mentioned. At a small distance from the prostate gland the 
spongy substance which invests it commences, and continues to 
its termination. After this spongy substance has arrived at the 
termination of the corpora cavernosa, it expands and forms a 
body of a particular figure which covers the extremities of the 
corpora cavernosa, and is denominated the Glans Penis. 

The Corpus Spongiosum begins at the distance of eight or ten 
lines from the anterior part of the prostate. It is much larger 
at its commencement than at any other part except the glans, 
and this enlarged part is called the Bulb. It surrounds the whole 
of the urethra, and, with the exception of the bulb and the glans 
penis, is of a cylindrical figure. It is formed by a membrane 
which has some resemblance to the coat of the penis, but is 
much thinner, and by a peculiar spongy substance, which occu- 
pies the space between the internal surface of this membrane 
and the external surface of the canal of the urethra. The mem- 
brane and the spongy substance, form a coat to the urethra, 
which, with the exception of the enlargement before mentioned, 
is about one line thick. After this spongy substance has arrived 



STRUCTURE OF THE CORPUS SPONGIOSUM. J 53 

at the termination, its coat adheres firmly to the coat of the 
penis. 

The Bulb, or first enlargement of the corpus spongiosum, is 
oblong, and rather oval in form ; it is marked by a longitudinal 
depression in the middle, which is very superficial. It consists 
entirely of the spongy substance above mentioned. 

The Glans Penis is also composed of the same spongy sub- 
stance, but the coat which covers it is more thin and delicate 
than that of the other parts of the urethra. The lower surface 
of the glans is fitted to the extremities of the corpora cavernosa, 
but it is broader than the corpora cavernosa, and therefore pro- 
jects over them on the upper and lateral parts of the surface of 
the penis. The edge of the prominent part is regularly rounded, 
and is denominated the Corona Glandis. 

— The contracted portion immediately behind the corona, is 
called the collum or neck. — 

Several small arteries pass to this spongy structure. The pudic 
artery, as it passes on each side to the corpora cavernosa, sends 
a branch to the bulb of the urethra. The same vessel, in the 
substance of the penis, also sends branches to the urethra ; and 
the artery on the back of the penis terminates in small branches, 
which penetrate the substance of the glans. 

By these vessels blood is carried to the spongy substance of 
the urethra, which is occasionally distended in the same manner 
that the cavernous bodies of the penis are distended during the 
erection of that organ. But the cellular structure of this organ 
is not so unequivocal as that of the corpora cavernosa ; for if it 
be injected with coloured wax, and corroded in the usual manner, 
the injected matter will exhibit an appearance which has the 
strongest resemblance to a convoluted vessel, like the vas de- 
ferens in the epididymis.* 

The Canal of the Urethra, 
Which conveys the urine from the bladder, is a very important 

* Mr. Hunter says, " that the corpus spongiosum urethrte and glans penis are 
not spongy or cellular, but made up of a plexus of veins. This structure is dis- 
cernible in the human subject; but is much more distinctly seen in many animals, 
as the horse," &c, — H. 



154 INTERNAL OR MUCOUS COAT OF THE URETHRA. 

part of the urinary organs. It consists of a vascular membrane 
with a smooth surface, which is perforated by the orifices of many 
mucous follicles, some of which are of considerable size. It is 
extremely sensible, and has so much power of contraction, that 
some persons have supposed muscular fibres to exist in its 
structure. 

It is differently circumstanced in different parts of its course. 
While surrounded with the prostate it adheres firmly to that 
body, seeming to be supported by it; and here its diameter is 
larger than it is farther forward. On the lower or posterior 
side of this portion of the urethra, is an oblong eminence, called 
Verumontanum, or Caput Gallinaginis, which commences at the 
orifice of the urethra, and continues throughout the whole portion 
that is surrounded by the prostate gland, terminating at the point 
of that body. The posterior extremity of this tubercle begins 
abruptly, and soon becomes thick and large; anteriorly it gradually 
diminishes to a line, which is sometimes perceptible for a con- 
siderable distance in the urethra, in a straight forward direction. 
In the upper edge or top of this body is a groove, which is pro- 
duced by a mucous follicle ; on the lateral surfaces, anterior to 
the middle, are the orifices of the common ducts of the vesicular 
seminales, and vasa deferentia, (see page 145,) which are suffi- 
ciently large to receive a thick bristle. Near these, on each side, 
are five or six smaller orifices of the excretory ducts of the 
prostate gland. At the distance of an inch before the extremity 
of the bulb of the urethra, in the lining membrane, are the 
openings of two ducts, one on each side, that lead to small glan- 
dular bodies called Cowper's glands, which are situated on each 
side of the urethra below the bulb, but are covered by the acce- 
leratores urinse muscles. 

The diameter of the urethra lessens after it leaves the prostate. 
That portion of the canal which is between this gland and the 
bulb, without investment, and therefore called the membranous 
part, is the smallest in diameter. 

After it is invested with the spongy substance, it has a small 
enlargement, and then continues nearly of one size, until it arrives 
near the glans penis, when it again enlarges and alters its form, 



MUCOUS FOLLICLES OF THE URETHRA. ■. j- e 

being no longer cylindrical, but flattened. Its broad surfaces 
have now a lateral aspect. 

From the bulb of the corpus spongiosum to this last enlarge- 
ment, the appearance of the inner surface of the urethra is 
uniform. The membrane is thin and delicate, and in a healthy 
subject, who has been free from disease of these parts, is of a 
whitish colour; but blood-vessels are very perceptible in it. 
When it is relaxed, it appears to be thrown into longitudinal 
wrinkles; but it admits of considerable extension ; being some- 
what elastic : when extended, its surface appears smooth, as if it 
were covered with an epithelium. Mr. Shaw, of London, has 
described a set of vessels immediately below the internal mem- 
brane of the urethra, which, when empty, are very similar in 
appearance to muscular fibres. He says he has discovered that 
these vessels form an internal spongy body, which passes down 
to the membranous part of the l.rethra, and forms even a small 
bulb there. His preparation with a quicksilver injection of the 
part is certainly a very satisfactory proof of its existence.* 
Throughout the whole extent of this part of the urethra, are the 
orifices of a great many mucous ducts or sinuses, which pass 
obliquely backwards. Many of these are so small that they 
cannot be penetrated by a bristle, or probe of that size; but 
some are larger. It has not been observed that any glandular 
body immediately surrounds them, although they secrete the 
mucus with which the urethra is lubricated. On the lower side 
of the urethra, near the commencement of the glans penis, there 
is one or more of them, so large that their orifices sometimes 
admit the point of a small bougie.f 

These organs when inflame I, secrete the puriform discharge 
which takes place in gonorrhoea. — In a natural state they pro- 
duce the mucus which is constantly spread over the surface of 
the urethra, to defend it from the acrimony of the urine, and 
which passes away with that fluid unperceived. 

The surface of the urethra is endued with great sensibility, and 

* See Med. Chirurg. Transactions of London, vol. x. 

t They were discovered by Plazzoni, of Padua, in 1621. Their number, ac- 
cording to Loder, amounts to about 65. See his j-lates.— h. 



J 56 SITUATION OF THE MUSCLES. 

is therefore liable to great irritation from contact with any rough 
body or any acrid substance. Irritation, thus excited, induces a 
state of contraction, which is particularly remarkable, as no 
muscular fibres are to be seen in its structure. When a bougie 
has been passed into the urethra for a considerable distance, if 
it cannot proceed the whole way, it sometimes happens that the 
instrument will be discharged by a steady uniform motion, which 
seems to proceed from a progressive contraction of the urethra, 
beginning very low down. At particular times, after the urethra 
has been much irritated, it will not receive a bougie, although at 
other times a bougie of equal size may be passed to the bladder 
without opposition. This cannot depend upon that elasticity 
which was noticed before.* 

Upon the two crura of the penis, or the beginning of the cor- 
pora cavernosa, are fixed the muscles called Erectores Penis, 
which are described in the first volume.f These muscles cover 
the crura of the penis from their origin to the junction, and not 
only compress them, but also influence the motion of the penis 
when it is distended. 

The bulb of the urethra is covered by a muscular coat, called 
the Accelerator Urince, which has the effect of driving forwards 
any fluid contained in the cavity of the urethra, and also of giv- 
ing the same direction to the blood in that part of the corpus 
spongiosum. There is also the Transversus Perinei on each 
side, that passes transversely from the tuberosity of the ischium 
to the bulb of the urethra. — Finally, the lower part of the sphinc- 
ter ani muscle, which is nearly elliptical in form, is inserted by 
its anterior point into the muscular covering of the bulb of the 
urethra. Upon removing the integuments, these muscles are in 
view ; and the course of the urethra from the bladder is con- 
cealed, particularly by the anterior point of the sphincter ani. 
When the sphincter ani is dissected away from its anterior con- 

* Sir Everard Home, whose professional opinions are of great weight, has lately 
described in the Transactions of the Royal Society, the appearance of the lining 
membrane of the urethra, when viewed through a microscope of great powers. 
From this paper, it seems that he is fully convinced of its muscular structure. — H. 

t See description of " Muscles about the Male Organs of Generation," vol. 1, 
page 306. 



LENGTH OF THE URETHRA. 157 

nexions, and the cellular and adipose substance, which is some- 
times very abundant, is also removed, the lower surface of the 
membranous part of the urethra may be brought into view, as it 
proceeds from the prostate gland to the bulb of the corpus spon- 
giosum.* 

When the accelerator urinas is removed from the bulb of the 
urethra, there will appear two bodies, which have some resem- 
blance to flattened peas. They lie one on each side of the 
urethra, in contact or nearly so with its bulb, and from each 
gland proceeds an excretory duct of an inch and a quarter in 
length between the corpus spongiosum and the lining membrane 
of the canal of the urethra, and opens into the latter. Its orifice 
is found with some difficulty, but is large enough to admit a 
bristle. These are Cowper's glands.f 

The penis is connected to the symphysis pubis by a ligament- 
ous substance, which proceeds from the back or upper surface 
of the organ to the anterior part of the symphysis, and connects 
these parts firmly to each other, called ligamentum suspensorium 
penis. 

Thus constructed, of the corpora cavernosa and the urethra 
with its corpus spongiosum, and attached to the pelvis as above 
mentioned, the penis is invested with its integuments in the fol- 
lowing manner. 

— The entire length of the urethral canal from its commence- 
ment at the back part of the prostate gland, that is at the neck of 
the bladder, to its external orifice in the glans penis, varies in dif- 
ferent subjects when distended or gently drawn out, from eight to 
ten inches. The difference in length in different individuals is 
found to depend upon the greater or less developement of the 

* The natural situation of the membranous part of the urethra, and of the pro- 
state gland, as well as their relative position with respect to the sphincter ani, rec- 
tum, &.c. can be best studied by a lateral view of the contents of the pelvis ; which 
is to be obtained by removing carefully one of the ossa innominata, and dissecting 
the parts which were enclosed by it. 

t These glands were discovered by Mery, in 1684, and described by Cowper,in 
1699. A third gland, smaller than the preceding, connected with the curve of the 
urethra under the symphysis pubis, was discovered by Cowper, and Morgagni 
speaks of having observed a fourth. — h. 

VOL. II. 14 



158 LENGTH OF THE URETHRA 

penis from the bulb of the urethra outwards ; the length of the 
membranous and prostatic portions being nearly the same in all 
adult subjects. The membranous portion of the urethra extends 
from the bulb to the anterior margin of the prostate, and is about 
three quarters of an inch long ; it is rather longer on its upper 
than its lower surface, in consequence of the extension of the pen- 
dulous portion of the bulb backwards. In place of the spongy 
portion, it is covered on its outer surface with a thin layer of pale 
cellulo-muscular fibres like that forming the neck of the bladder 
(see page 125,) with which it is continuous.* 
— The prostatic portion of the canal is of the length of the gland, 
and varies from fifteen to eighteen lines. It is conoidal in its 
shape, the base of the cone being on the side of the bladder, and 
its narrowest part or apex continuous with the membranous por- 
tion. In consequence of this shape, small calculi frequently drop 
into it from the bladder, and sometimes imbed themselves in the 
substance of the prostate gland. The direction of the prostatic 
and membranous portions of the urethra is from above down- 
wards and backwards, towards the neck of the bladder, form- 
ing a curve, the concavity of which is towards the pubis. 
The spongy or external portion of the canal forms a curve in the 
opposite direction, so that the whole canal in its undistended 
state, resembles somewhat in shape the italic 5. When the 
penis is drawn upwards and forwards, both curves as Amusat has 

* Wilson has described a muscle, (see vol. 1, p. 307,) situated one upon each side 
of the membranous portion of the urethra, called the musculus constrictor urethra? 
or pubo-urelhralis. It is oblong, quadrilateral, and flattened from without inwards. 
It arises from a short tendon on the back part of the pubis, near the symphysis. It 
increases in size as it descends, embraces closely the membranous portion of 
the urethra, and at the lower surface of the latter is closely connected with its fel- 
low of the opposite side ; so that the two form as it were a muscular ring around 
the urethra. In front it is usually connected with the posterior part of the accelera- 
tor urinas muscle, and below it is connected to the levator ani. It appears to me to 
form a part of the latter muscle, and to act as a constrictor of the urethra to the male 
and of the vagina in the female. These are voluntary muscles, according to Muller, 
and are the principal agents by which wc exercise any voluntary control over the 
discharge of urine. 

When spasmodically contracted, they compress the urethra, and often render 
the passing of a catheter along this portion of the canal impossible, till the spasm 
is relaxed by medicinal means. — p. 



INTEGUMENTS OF THE PENIS. 



159 



shown, are nearly effaced, and a straight instrument may, with 
facility, be passed into the bladder.— 

Integuments of the Penis. 

The glans penis, the structure of which has been already de- 
scribed, is covered by a continuation of the skin which appears 
altered in its texture so as to resemble in some respects the skin 
of the lips, and in like manner is covered by a delicate produc- 
tion of cuticle. 

Around the corona of the glans, especially on its upper part, 
there are whitish tubercles, glandulce Tysoaii, which are of differ- 
ent sizes in different persons, but always very small. The skin 
adheres firmly to the whole extent of the corona of the glans, 
and is very delicate in its structure, as it continues from the glans 
upon the body of the penis ; but it gradually changes so as to 
assume the appearance and structure of a common skin, and 
continues in this state over the penis. The adhesion of the skin 
to the ligamentous coat of the corpora cavernosa also becomes 
more loose, owing to the quantity and texture of the cellular 
substance which connects them. The skin, thus connected to 
the penis, has commonly more length than that organ, even in its 
extended state. In consequence of this greater length, and of its 
adhering firmly around the corona glandis, it necessarily forms 
a circular fold or plait, which varies in size according to the 
length of the skin. This fold is generally situated at the com- 
mencement of the firm attachment of the skin to the body of the 
penis, or around the glans ; but it may be formed any where 
upon the body of the penis by artificial management. 

This duplicature, or fold of the skin, when it takes place so as 
to cover the glans* is called the Prepuce ; and the skin, which is 
very tender and delicate for some distance from the glans, forms 
that surface of the prepuce which is in contact with the glans 
when it covers that body. 

There is also a small fold of the skin, which is longitudinal in 
its direction, that commences at the orifice of the urethra, and 
extends backwards on the lower surface of the penis. It is unva- 
rying in its position, and is called Frenum. 



IQQ INTEGUMENTS OF THE PENIS. 

It is a general observation, that adeps is not found in the cel- 
lular substance which connects the skin to the body of the penis ; 
but this cellular substance is distended with water in some hy- 
dropic cases. 

From the glands of Tyson, and from small follicles on each 
side of the fraenum, is secreted an unctuous fluid, (Smegma pre- 
putii,) which, when allowed to continue, becomes inspissated, and 
acquires a caseous consistence and colour, as well as a peculiar 
odour. It sometimes also acquires an acrimony which produces 
inflammation on the surface with which it is in contact, as well 
as the copious secretion of a puriform fluid. 

The distribution of the pudic artery in the penis has already 
been mentioned ; and a farther account of its origin and progress 
to its destination, will be found in the general account of the 
arteries. Sometimes small branches of the external pudic arte- 
ries, which originate from the femoral, are extended to the 
penis; and it has been asserted, that branches of the middle 
haemorrhoidal artery have also been found there, but this does 
not often occur. 

The Feins of the penis are of two kinds ; those which origi- 
nate in the corpora cavernosa, accompany the corresponding 
branches of the pudic artery, but communicate more or less 
with the plexus of veins on the lower and lateral part of the 
bladder. There is also a great vein, which occupies the groove 
on the back of the penis, between the corpora cavernosa, that 
appears particularly appropriated to the corpus spongiosum 
urethra; for it originates in the glans penis, and receives 
branches from the urethra as it proceeds backwards. There 
are often two of these veins, one in the groove, and the other 
more superficial : they generally unite near the root of the penis. 
The common trunk then passes between the body of the penis 
and the symphysis pubis, and terminates in a plexus of veins at 
the neck of the bladder, which is connected to the plexus above 
mentioned on the lower and lateral parts of the same viscus. 

The Absorbent Vessels of the penis take two different direc- 
tions on each side. Those which arise from the integuments 
generally, unite so as to form a few trunks on the back of the 



PERINEAL FASCIA. ](jl 

penis, which divide near the root of the organ, and proceed to 
the glands of the groin. Those which originate from the inte- 
rior parts of the penis, accompany the blood-vessels, and termi- 
nate in the plexus of lymphatics in the pelvis. 

It ought to be noted, that the superficial lymphatics generally 
enter the upper inguinal glands. — The deep-seated lymphatics, 
which originate in the glans penis and the cavernous structure, 
run with the cavernous artery of the penis, directly into the 
pelvis. Hence in chancres of the glans, the venereal poison may 
be introduced into the system without traversing the glands of 
the groin. — 

The Nerves of the penis are principally derived from the lower 
sacral nerves, which unite in the plexus that forms the great 
ischiatic. From these nerves a branch on each side originates, 
which passes, like the pudic artery, between the sacro-sciatic 
ligaments. In this course it divides into two branches, one of 
which passes below to the muscles of the penis and urethra, and 
to the contiguous parts ; and some of its branches seem finally 
to terminate in the dartos : the other branch proceeds along the 
crura of the pubis and ischium, and passing between the sym- 
physis pubis and the body of the penis, arrives at the upper sur- 
face or dorsum of the penis, along which it continues on the 
outside of the veins to the glans, in which it terminates. In this 
course it sends off several branches, some of which terminate in 
the integuments of the penis. 

Fascia of the Perineum. 

[There are several fascia) and ligaments about the perineum, 
which should be connected with the account of its viscera. Im- 
mediately beneath the skin of the perineum is the Perineal 
Fascia, a thin but strong membrane, which extends from bone 
to bone, occupying the space between the anus and the posterior 
part of the scrotum. It is rather better seen in lean subjects than 
in fat ones, for in the latter it is converted in part into adipose 
membrane. When a rupture occurs in the posterior part of the 
urethra, this fascia prevents the urine from showing itself imme- 

14* 



162 TRIANGULAR LIGAMENT OF THE URETHRA. 

diately in the perineum, and drives it into the cellular structure 
of the scrotum. 

Immediately beneath the perineal fascia are placed the mus- 
cles ; when they are removed, the bulb of the urethra may be 
seen very advantageously, extending in the middle of the peri- 
neum almost to the anus. It is not loose and pendulous, but is 
attached by its pelvic surface to the triangular ligament of the 
urethra. This ligament is a septum between the perineum and 
the pelvis, and connects itself to the pelvic or internal edges of 
the rami of the pubis and ischi as far down as the organs of the 
crura penis. It extends from the arch of the pubis to the line 
mentioned, and fills up all the space between the bones of the 
opposite sides. It consists of two lamina, and Cowper's glands 
are placed between them. About an inch below the symphysis 
pubis a perforation is made in this ligament for the passage of the 
membranous part of the urethra. 

Just below the symphysis pubis, between the two lamina of the 
triangular ligament, is placed a much stronger ligament called 
the pubic, which is about half an inch broad ; its lower edge is 
thick and rounded.]* 

After an examination of the relative situation of the muscles and blood-ves- 
sels of the male organs of generation, there appears reason to doubt, 
whether the erection of the penis can be referred to pressure upon the 
veins which return from that organ. Albinus has written on this subject. 
See Academicarum Annotationum, lib. ii. caput xviii. Haller has also con- 
sidered it, and stated the opinions of several anatomists, in his Elementa 
Physiologiae, torn. vii. page 555. 

The manner in which the urine is confined in the bladder does not appear 
to be clearly understood. The connexion of the neck of the bladder with 
the prostate, and the appearance of the contiguous parts of the bladder, 
do not render it probable that these parts act like a sphincter. The late 
J. Hunter, who paid great attention to the functions of these organs, was 
very decided in his opinion that the contraction of the urethra produced 
the effect of a sphincter of the bladder. He has published some very in- 
genious observations respecting the manner in which urine is discharged 
from the bladder, in his Treatise on the Venereal Disease, part iii. chap- 
ter ix. 

* For farther detail on the subject of the fasciae of the pelvis, see Lessons in Prac- 
lical Anatomy, by Dr. Horner. » 



GENERAL ANATOMY OF ERECTILE TISSUE jgg 

Mr. Hunter also long since asserted, that the vascular convoluted appear- 
ance of the corpus spongiosum urethra was more distinct in the horse 
than the man. In the fifth volume of Le$on's d'Anatomie Comparee of 
Cuvier, the very learned and ingenious author confirms the declaration of 
Hunter, respecting the vascular convolutions of the corpus spongiosum of 
the horse. He states, that the corpora cavernosa of the penis of the ele- 
phant appear to be filled in a great degree with the ramifications of veins, 
which communicate with each other by such large and frequent anasto- 
moses, that they have a cellular appearance. A similar structure exists 
in the horse, camel, bullock, deer, &c. ; and in them all these communi- 
cating branches can be distinguished from those which extend the whole 
length of the penis. 

The corpus spongiosum urethra, according to M. Cuvier, is constructed in a 
similar manner. From these facts he is induced to believe that this struc- 
ture pervades the whole class of mammalia. 

General Anatomy of Erectile Tissue. 

— The term erectile tissue, tela erectilis, was first adopted by 
Dupuytren and Rullier, to indicate various parts which are prin- 
cipally composed of blood-vessels, intimately interwoven with 
nerves, and which, under various causes of excitement, mecha- 
nical or sensorial, are rendered turgid and prominent, or thrown 
into a state of erection by a sudden influx of blood. This sys- 
tem includes the corpus cavernosum penis, corpus spongiosum 
urethra, clitoris, nymphas, plexus retiformis vaginas, nipples, cu- 
taneous papillae, mucous villi, red borders of the lips, and, accord- 
ing to Harrison, the seminal tubercle or caput gallinaginis. It 
is supposed by some to exist in the iris, and Beclard is disposed 
to include in this tissue the spleen. It is seen also in other posi- 
tions in the inferior animals, as in the wattles of the turkey, and 
tongue of the chameleon. It is developed also accidentally in 
different parts of the body, as in erectile tumours, (aneurisms from 
anastomosis,) and in fungus hasmatodes. In some of the organs 
it is enclosed in a fibrous sheath, which limits the extent of the 
expansion and determines its form. Its developement, however, 
is found more perfect in some organs than the rest, and it is most 
so in the corpus cavernosum penis, and corpus spongiosum ure- 
thra?. In these parts it has principally been made the subject 
of investigation. The commonly received opinion, and which 



164 



GENERAL ANATOMY OF ERECTILE TISSUE. 



Fig. 63. 



is kept up by the appearance which anatomical preparations 
present, when the common cellular tissue of the parts is rilled 
with wax, to exhibit their general form, is this ; that the erectile 
tissue consists of loose elastic 
tissue divided into innumerable 
cells, into which, during erection, 
blood is poured by the arteries 
and taken up subsequently by the 
veins. Such was the opinion of 
Ruysch, Haller, and Bichat. Ve- 
salius, Mascagni and Hunter, 
were of the opinion that the 
tissue was made up of a multi- 
tude of arteries and veins, the 
latter predominating greatly in 
number, closely interwoven, and 
resting upon the cells ;* which 
are formed by processes sent in- 
wards from the general invest- 
ing sheath of the parts (involu- 
crum) which divide the interior 
into cells, like the septse which 
divide the cavity of an orange, 
and which form a sort of scaf- 
folding for the support of the ves- 
sels. This opinion has been sup- 
ported by Cuvier,Tiedemann, Be- 
clard and Weber, who assert that 
a structure corresponding to it is 
discernible in man, and is par- 
ticularly obvious in the horse 
and other large animals. The 
annexed cut from Moreschi, shows the congeries of vessels as 
they exist in the injected state in the glans penis, which are prin- 
cipally veins, and are characterized by their number, tenuity and 
softness, and which empty into the superficial veins of the penis. 




* See Erectile Tissue, Diet. Des Sciences Medicales, by Dupuytren and Rullier. — P. 



GENERAL ANATOMY OP ERECTILE TISSUE. 



165 



— Professor Muller has recently discovered in the structure of 
the corpus cavernosum penis, two sets of arteries forming rami- 
fications from the common trunk ; the arteria profunda. One of 
these consists of the ordinary nutritious arteries of the part, which 
ramify over the cells and terminate in the capillary veins, and 
through which, in the unexcited state, all the blood flows that is 
conveyed by the profunda. The other sets he calls the arteria 
helicincB, see Fig. 64, which is a magnified representation of a part 
of the profunda with its helicine branches, so 
named from their resemblance to the tendrils of 
the vine ; they are much shorter, however, in 
proportion to their thickness, than the compari- 
son would seem to indicate. These arterie be- 
come dilated during the state of erection, and 
receive all the blood imported by the profunda, 
in increased quantities during the period of 
excitement. These arteries maybe seen with 
the lens or even with the naked eye, in the 
back part of the corpus cavernosum penis, 
when the profundi his been injected with 
coloured size, the corpus cavernosum subsequently slit open, and 
all the injection which has escaped into the cells, carefully washed 
away. These branches from the profunda are short, being about 
a line in length and a fifth of a millimetre* in diameter, and are 
of the same size whether they are derived from the larger 
branches or the finest twigs. 

— The arterise helicinas, sometimes branch off singly, sometimes 
in little bundles from three to ten in number ; in which case they 
originate by a common trunk. They project constantly into 
the cells of the spongy substance, which Muller considers 
venous cavities, and either terminate abruptly, or swell out into 
a club-like process without again subdividing. These vessels 
when they project into the venous cavities, according to Muller, 
are not entirely naked, but are covered by a delicate membrane, 
which, under the microscope, appears granular, and when the 
arteries form a bundle, the whole bundle is covered by a 

* A millimetre equals the 0.03937 of an English inch. 




1(J(5 GENERAL ANATOMY OF ERECTILE TISSUE. 

gause-like membrane. Muller considers this membrane as 
performing an important part in producing the phenomena of 
erection. These arteries have neither on their sides or extremi- 
ties, any openings discoverable with the microscope ; and when 
the blood, as is probable, escapes from them in large quantities 
into the venous cells during erection, it must either escape 
through invisible openings or by orifices which become enlarged 
by the dilatation of the arteries. These helicine arteries appear 
to have been seen by Weber, and figured in his plates, though not 
under that particular name, (Vide Tub. xxvi. Figs, xxvii. xxviii.)* 
— The discovery of these vessels by Muller, though they do not 
by any means fully explain to us the phenomena of erectility, 
goes far towards reconciling the two conflicting opinions enter- 
tained upon this subject. That the cells formed by the septa) of 
the corpora cavernosum and spongiosum penis, are lined with 
the lining membrane and continuous with the cavity of the veins, 
there can, I think, be little doubt. For with the injecting pipe 
plunged at random in the cells of these parts, we invariably suc- 
ceed in filling the superficial veins of the penis; and by inserting 
a pipe in the vena magna ipsius penis, we are equally success- 
ful in distending with injecting matter, the spongy cells. In these 
cells ramify the helicine arteries of Muller, by which the blood 
is conveyed with which the cells are distended by an injection 
throughout the arteries during erection. 

— How far any coarctation or compression of the superficial 
veins at the root of the veins may assist this accumulation of 
blood in the cells, or whether it takes place at all, is not known. 

* Mttller's Archives, or London Medioal Gazette, No. 423, 



FEMALE ORGAN'S OF GENERATION. jq^ 



CHAPTER VI. 

OF THE FEMALE ORGANS OF GENERATION.* 

The female organs of generation consist of the Uterus and 
Ovaries, with their appendages ; and of the Vagina, with the 
structure which surrounds its external orifice. The uterus is 
situated in the pelvis, between the bladder and rectum ; and the 
ovaries are on each side of it. The vagina is a very large mem- 
branous canal, which passes from the uterus downwards and 
forwards, also between the bladder and rectum, and opens ex- 
ternally. 

Connected with the orifice of the vagina are several bodies, 
which are called the external parts of generation, in order to dis- 
tinguish them from the uterus and ovaries, and their appendages, 
and also from the canal of the vagina ; which are called the 
internal farts. 

The bladder of urine lies above and in contact with the va- 
gina : the urethra is also intimately connected with it. The de- 
scription of the bladder and urethra is therefore placed at the end 
of this chapter. 

Of the External Parts of Generation. 

— All the external parts of generation are included, under the 
general term of vulva. They consist of the mons veneris, the 
labia externa, the fourchette, the fossa navicularis, the clitoris, 
the nymphse, and the hymen. — 

The adipose membrane, immediately anterior to the symphysis 
pubis, and on each side of it, forms a considerable prominence 
in females, which, at the age of puberty, is covered with hair, as 
in males. This prominence is denominated the Mons Veneris. 

* For a very ablo and interesting account of the history and function of these 
organs, and of embryology, sec Dunglison's Physiology, vol. 2, 4th edit. — r. 



168 LABIA EXTERNA.— CLITORIS. 

The exterior orifice commences immediately below this. On 
each side of this orifice is a prominence continued from the mons 
veneris, which is largest above, and gradually diminishes as it 
descends. These prominences have some hair upon them. They 
are called the Labia Externa. Their junction below is denomi- 
nated the Fourchette. — The fourchette or frenulum vulva, is a 
delicate duplicature of the lining membrane, which forms the pos- 
terior commissure of the labia externa. In the virgin state it 
contracts the opening into the vagina, and behind it that canal 
forms a little depression or pouch. It is usually ruptured or ef- 
faced during the first act of parturition. — The space between 
the place of their junction and the anus is rather more than an 
inch in extent, and is denominated the Perineum. 

— The perineal space between the vagina and rectum, extends 
upwards for about three inches, and terminates in a point ; it is 
filled chiefly with cellular and adipose matter, through which many 
nerves and blood-vessels run, and is called the perinea] triangle. 
This shares in the distention of the vagina during parturition, so 
that in the passage of the head of the child, there appears only 
interposed between it and the cavity of the rectum, a thin mem- 
branous layer. — 

As the skin which forms the labia is continued internally, it 
becomes more thin and soft, and is covered by a more delicate 
cuticle. It is also more or less florid, and secretes a peculiar 
mucus. 

In the upper angle, formed by the labia externa, is the upper 
extremity and glans of the clitoris. 

The Clitoris is a body which has a very strong resemblance 
to the penis, but there is no urethra attached to it. It has two 
crura of considerable length, which originate, like those of the 
penis, from the crura of the pubis and ischium, and unite at the 
symphysis of the pubis so as to form a body, which is not much 
more than an inch in length, and is broad in proportion. The 
extremity of this organ, called the Glans of the Clitoris, forms a 
small tubercle, which is covered above and on the sides by a 
small plait or fold of the skin denominated Prepuce. These parts 



NYMPHS. 169 

are lubricated by a secretion similar to that which is observed 
round the glans penis. 

The crura of the clitoris have muscles similar to the erectores 
penis. The interior structure of the Clitoris is very similar to 
that of the corpora cavernosa of the penis, or the corpus spon- 
giosum of the urethra. It appears constructed for a similar dis- 
tention, and is endued with the same sensibility as the penis. The 
two lateral parts are also separated from each other by a sep- 
tum, resembling that of the penis. It is united to the symphysis 
pubis by a ligament. 

The Prepuce of the clitoris has a semicircular form : below 
its extremities two folds or plaits commence, one on each side, 
which are situated obliquely with respect to each other, so as to 
form an angle. These folds are denominated the JVymphce. 

The JVymphce or Labia Interna extend from the clitoris down- 
wards nearly as far as the middle of the orifice of the vagina. 
They are situated within the external labia, and are formed by 
the skin after it has become more delicate in its texture. Their 
surface, however, is often somewhat corrugated. There are 
many blood-vessels in their internal structure, and it is supposed 
they are occasionally somewhat tumid. They are flat, and then- 
exterior edge is convex ; so that they are narrow at their extre- 
mities, and broad in the middle. Their breadth is very variable, 
and in some instances is great. In a majority of cases, it is 
equal to one-fourth of their length. Their colour in young 
subjects is of a bright red ; in women advanced in years, and 
who have had many children, they are of a brown red, and 
sometimes of a dark colour. 

The use of these parts is not very evident. They have been 
supposed to regulate the course of the urine as it flows from the 
urethra, but their effect in this respect is not great. They have 
also been supposed to favour the necessary enlargement of the 
parts in parturition. 

— The nymphai are larger usually in blacks than whites. 
They descend some distance below the labia externa, and consti- 
tute the tabliers or aprons of the Hottentot females. The nym- 
phce are very vascular. 

VOL. II. 15 



170 HYMEN—VAGINA. 

— The triangular and slightly concave depression, between the 
labia interna, about an inch or an inch and a quarter in length, 
is called the Vestibulum. The space between the posterior part 
of the orifice of the vagina, and the fourchette is called the Fossa 
Navicularis. On the surface of both these parts are observed 
reat number of mucous follicles. — 

The orifice of the urethra is situated about an inch and one 
quarter farther inward than the clitoris. It is often rather less 
than the diameter of the urethra, and is somewhat protuberant. 
The orifices of mucous ducts are to be perceived around it. 

The orifice of the urethra is at the commencement of the 
canal of the vagina. Immediately within this orifice is situated 
the membrane denominated Hymen. 

The Hymen is an incomplete septum, made by a fold or dupli- 
cature of the membrane which forms the surface contiguous to 
it. Sometimes it is circular, with an aperture in the centre. 
Sometimes it has a resemblance to the crescent, the aperture 
being at the upper part of it. The hymen has frequently been 
found without a perforation, and has therefore prevented the dis- 
charge of the menstrual evacuation. It is generally ruptured 
in the first intercourse of the sexes; and some small tubercles, 
which are found on the surface of the vagina near the spot 
where it was situated, are supposed to be the remains of it. 
These tubercles are called CarunculcB Myrtiformes. 

— Dr. Duvernoy, has found the hymen to exist in many of the 
inferior animals, in which it varies in regard to form, precisely 
as it does in the human race. — 

Of the Vagina. 

The canal of the vagina, commencing at the hymen and the 
orifice of the urethra, is rather more narrow at its beginning 
than it is farther inward. From this place it extends backwards 
and upwards, and partakes in a small degree of the curve of the 
rectum : while the bladder, which is above it, and rests upon it, 
increases the curvature of the anterior part. It is much larger 
in women who have had children than in those who have not. 

—In the virgin state at puberty, its length is about five inches, 



CORPORA CAVERNOSA VAGINAE. 171 

and its breadth, when moderately distended, one inch. In a 
natural state of the parts, there is no cavity, the surfaces of the 
mucous membrane being in contact. In women who have borne 
many children, its length diminishes, and its breadth increases in 
inverse proportion with each other. — 

The membrane which lines the vagina resembles to a certain 
degree, the membranes which secrete mucus in different parts ot 
the body. Its surface appears to consist of very small papilla?; 
and at the anterior extremity of the vagina it forms a great 
number of rugae, which are arranged in a transverse direction, 
both on the part of the vagina connected to the bladder, and on 
that part which is connected to the rectum, while the lateral 
parts of the vagina are smooth. These rugae are most promi- 
nent in the middle; so that a raised line appears to pass through 
them at right angles. This line extends from without inwards. 
The rugae on the part next to the bladder are the strongest. 

This arrangement of the surface of the vagina does not extend 
beyond the external half of the canal : on the internal half part, 
or that nearest the uterus, the surface is smooth. 

The rugae are considerably diminished in women who have 
had children. 

Throughout this surface are to be seen, in some cases with 
the naked eye, the orifices of mucous follicles or ducts, which 
occasionally discharge considerable quantities of mucus. 

— Near the external orifice of the vagina, exist a couple of 
little glands, somewhat resembling those of Cowper, which dis- 
charge through their ducts a lubrifying mucus on the surface of 
the membrane. — 

Exterior to the lining membrane of the vagina is a dense cel- 
lular structure, which has not yet been completely investigated : 
it is of a lightish colour, and has some resemblance to the tex- 
ture of the body of the uterus. It is very vascular, and appears 
to be of a fibrous structure. It may be very much distended, 
and seems to have a contractile power. 

At the anterior extremity of the vagina, on each side of it, 
there is superadded to this, a cellular, or vascular substance, 
from eight lines to an inch in breadth : which, when cut into, 



172 UNIMPREGNATED UTERUS. 

resembles the corpora cavernosa, or the corpus spongiosum of 
the penis. These bodies commence near the body of the clitoris, 
and extend downwards on each side of the vagina. They have 
been called Plexus Retiformis, and Corpora Cavernosa Vagina, 
and are occasionally distended with blood, like the clitoris and 
penis. 

These corpora cavernosa are covered by muscular fibres, 
which pass over them on each side from the sphincter ani to the 
body of the clitoris ; to each of which organs they are attached. 
These fibres constitute the sphincter vagina muscle, and con- 
tract the diameter of the vagina at the place where they are 
situated.* 

The transversus perinei muscles also exist in the female. 
They pass from the tuberosities of the ischia, and are inserted 
into a dense whitish substance in the perineum, to which the 
anterior extremity of the sphincter ani is likewise attached. 

The vagina is in contact with the rectum behind ; the bladder 
lies upon it and anterior to it. A small portion of peritoneum, 
to be reflected to the rectum, is continued from the uterus upon 
the posterior part of it. The lateral portions of it are invested 
with cellular substance. The anterior extremity of the uterus, 
which is called the Os Tineas, projects into it from above. 

Of the Uterus, the Ovaries and their Appendages. 

The Uterus has been compared to a pear with a long neck. 
There is, of course, a considerable difference between the body 
and neck ; the first being twice as broad as the last. Each of 
these parts is somewhat flattened. 

In subjects of mature age, who have never been pregnant, the 
whole of the uterus is about two inches and a half in length, and 
more than one inch and a half in breadth at the broadest part of 
the body : it is also near an inch in thickness. 

It is generally larger than this in women who have lately had 
children. 

* These two muscular bands, which when conjoined together form the sphincter 
vaginae, have a similar origin and insertion and correspond with the acceleratores 
urina? muscles of the male. — p. 



LIGAMENTS OF THE UTERUS. I73 

The uterus is situated in the pelvis between the bladder and 
rectum, and is enclosed in a duplicature or fold of the peritoneum, 
which forms a loose septum that extends from one side of the 
pelvis to the other, and divides it into an anterior and posterior 
chamber. The posterior surface of this septum is opposed to 
the recium, and the anterior to the bladder. The two portions 
of this septum which are between the uterus and the lateral parts 
of the pelvis, are called the Broad Ligaments. 

On the posterior surface, the Ovaries are situated on each side 
of the uterus, being enclosed by a process of the ligament or 
septum. Above them, in the upper edge of the septum, are the 
Fallopian Tubes, which are ducts that commence at the upper 
partof the uterus on each side, and proceed in a lateral direction 
for some distance, when they form an angle and incline down- 
wards to the ovaries. These ducts are enclosed between the 
two lamina of the septum for the greater part of their length. 

The peritoneum which forms the septum, is reflected from it, 
posteriorly, to the rectum, and the posterior surface of the pelvis, 
and anteriorly to the bladder. In its progress in each direction, it 
forms small plaits or folds; two of which extend from the uterus 
to the rectum posteriorly, and two more to the bladder ante- 
riorly : these are called the Anterior and Posterior Ligaments of 
the Uterus. 

The other ligaments, which proceed more immediately from 
the uterus, are called the Round Ligaments. These arise from 
each side of the uterus, at a small distance before and below the 
origins of the Fallopian tubes, and proceed in an oblique course 
to the abdominal rings. These ligaments are also invested by 
the peritoneum. They pass through the rings and soon terminate. 

In the body of the uterus is a cavity, which approaches to the 
triangular form, and from which a canal proceeds through its 
neck. This cavity is so small that its sides are almost in contact, 
and the canal is in proportion ; so that this organ is very thick 
in proportion to its bulk. 

The substance of which the uterus consists is very firm and 
dense: it is of a whitish colour, with a slight tinge of red. There 
are many blood-vessels, with nerves and absorbent vessels, in its 

15* 



274 FIBRES OF THE UTERUS. 

texture. The nature and structure of this substance has not yet 
been precisely ascertained. It appears very different indeed 
from muscle ; but the uterus occasionally contracts, with great 
force, during labour. It is not rendered thin by its enlargement 
during pregnancy, and the blood-vessels in its texture are gene- 
rally enlarged at that time. 

— The proper tissue of the uterus in its ordinary condition, is 
of a grayish colour, and of a density almost cartilaginous, es- 
pecially in its neck. It is composed of fibres, the nature and 
arrangement of which it is then impossible to determine. When 
enlarged by gestation, its tissue is soft, reddish, very dilatable, 
contractile, and presents all the characters of muscular tissue. 
Its fibres* are arranged in the following manner : — 
— In the body of the uterus they form two layers, one superficial 
and one deep-seated. The former is composed first, of a vertical 
fasciculus, which runs over the anterior and posterior faces of 
the organ; of a second fasciculus, which runs along the superior 
border of the fundus, and of several other oblique layers, which 
may be traced upon the Fallopian tubes, round ligaments, broad 
ligaments, and ligaments of the ovaries. In many animals, as 
in the cow, we find the broad ligament a mass of muscular fibres 
continuous with the uterus. 

— The second or deep-seated, form two cones, which are con- 
nected by their bases upon the median line, and by their apices 
to the Fallopian tubes. The neck of the uterus is composed en- 
tirely of circular fibres, closely compacted together. — 

Exteriorly, the uterus is covered by the peritoneum, as has 
already been mentioned. Internally it is lined with a delicate 
membrane that has some resemblance to those which secrete 
mucus, and is generally of a whitish colour, abounding with 
small orifices that can be seen with a magnifying glass. This 
membrane is so intimately connected to the substance of the 
uterus, that some anatomists have supposed it was merely the 
internal surface of that substance, but this opinion is now gene- 

* The best description of the fibres of the uterus is that of Madame Boivin. 
Vide Maladies de l'Uterus, etc. by Mad. Boivin and A. Duges. Paris.— p. 



CAVITY OF THE UTERUS. J7/5 

rally abandoned. It is supposed that the colour of this membrane 
is more florid about the period of menstruation. 

The cavity of the uterus, as has been observed before, is 
triangular in form. When the organ is in its natural position, 
the upper side of this triangle is transverse with respect to the 
body, and the other sides pass downwards and inwards. In each 
of the upper angles are the orifices of the Fallopian tubes, which 
are of such size as to admit a hog's bristle. 

The two lower lines of the triangle are slightly curved out- 
wards at their upper extremities ; so that the upper angles of the 
triangle project outwards and the orifices of the Fallopian tubes 
are nearer to the external surface than they otherwise would be. 

The lower angle of the cavity of the uterus is occupied by the 
orifice of the canal, which passes through the neck of the organ; 
this orifice is from three to four lines in diameter. The canal is 
about an inch in length, and is rather wider in the middle than 
at either end. On the anterior and posterior portions of its 
surface are many small ridges which have an arborescent ar- 
rangement, one large ridge passing internally from the com- 
mencement of the canal, from which a number of other ridges 
go off in a transverse direction. These ridges extend nearly the 
whole length of the canal. In the grooves, between the ridges, 
are the orifices of many mucous ducts. 

— These folds or ridges all disappear during gestation, and 
their singular arrangement serves to explain, how the neck is 
capable, when expanded, of forming a third part of the general 
uterine cavity, at the latter period of gestation. — 

There are also on the surface a number of transparent bodies 
of a round form, equal in bulk to a middle-sized grain of sand, 
the nature and use of which is unknown. They have been called 
Ovula JVabothi, after a physiologist who published some specu- 
lations respecting their use, about the commencement of the last 
century. 

— These are now generally believed to be the mucous follicles 
of the neck of the uterus in a state of vesicular distention, the 
orifices of which have been obliterated. — 

The canal of the neck of the uterus is verv different from 



176 THE FALLOPIAN TUBES. 

other ducts, for it seems to be a part of the cavity to which it 
leads, and when the cavity of the uterus becomes enlarged in 
the progress of pregnancy, this canal is gradually converted into 
a part of that cavity. 

The lower extremity of the neck of the uterus is irregularly 
convex and tumid. The orifice of the canal in it, is oval, and so 
situated that it divides the convex surface of the neck into two 
portions, which are called the Lips. The anterior or upper 
portion is thicker than the other. 

This extremity of the uterus protrudes into the vagina, and 
is commonly called Os Tinea. As the anterior portion or lip is 
larger and more tumid than the posterior, the vagina extends 
farther beyond the os tineas on the posterior part than on the 
anterior. 

The Fallopian Tubes 

Are two canals, from four to five inches in length, which pro- 
ceed between the lamina of the broad ligaments, from the upper 
angles of the uterus, in a transverse direction, to some distance 
from the uterus, when they form an angle, and take a direction 
downwards towards the ovaries. 

They are formed, for a considerable part of their extent, by a 
substance which resembles that of which the uterus consists, and 
are lined by a membrane continued from the internal membrane 
of the uterus. Their extremities appear to be composed of mem- 
brane, which is rendered florid by the blood-vessels in its texture. 
At the commencement, their diameters are extremely small ; 
but they enlarge in their progress. This enlargement is gradual 
for the first half, and afterwards sudden ; the enlarged part is 
more membranous than the small part, and has a bright red co- 
lour. The large extremity is loose in the cavity of the pelvis, 
and is not invested by the lamina of the broad ligaments. Near 
the termination the diameter is often contracted ; after which 
the membrane which forms the tube expands into an open 
mouth, the margin of which consists of fringed processes : this 
margin is also oblique, as respects the axis of the tube; and the 
different fringed processes are not all of the same length; but the 



THE FALLOPIAN TUBES. I77 

longest are in the middle, and the others regularly diminish on 
each side of them : these processes constitute the Fimbria, of the 
Fallopian tubes. 

The internal surface of the large extremities of these tubes is 
extremely vascular; and there are some longitudinal fibres of a 
red colour to be seen on it. 

— More recent investigations into the structure of the Fallo- 
pian tubes, have shown that they are composed in some respect 
like the urethra : of a canal lined by a mucous membrane, and of 
an erectile spongy body without, like the corpus spongiosum. 
— When this spongy substance is distended by a fine size injec- 
tion, I have found it bowed upwards as if in a state of erection, 
and the Fimbria, or Morsus Diaboli, which are likewise rendered 
turgid, spread themselves out upon the ovary, so that the dilated 
funnel-shaped cavity of the tube is in contact with this organ. 
One or two of the longest of these fimbriae are usually attached 
to the external margin of the ovary. Sometimes they are all 
found adherent as a consequence of accidental inflammation. In 
a young girl dead six or seven weeks after conception, Madame 
Boivin, found the trumpet-shaped extremity of the left tube curved 
over the ovary so as to cover it almost entirely, and all the fim- 
briae strongly adherent to its surface. At the orifice of the 
tube was a membranous cyst, of the size of a hazle-nut, filled 
with a yellowish serum, and covered with minute red vessels. 
This interesting fact is in support of the function attributed to 
these organs during fecundation : that of grasping the ovary 
with its fimbriae, and sucking in the ovum when detached, which 
in ordinary cases it transmits to the womb. 
— There is reason to believe, that the pathological changes of the 
distal extremity of this tube, are frequent cause of sterility. It 
is so frequently found diseased in the class of subjects with 
which our anatomical rooms are supplied, that it is even difficult 
to procure a perfectly healthy specimen of the parts. The mor- 
bid changes that I have most frequently met with, are an agglu- 
tination of the end of the tube to the ovary or broad ligaments, 
its occlusion by inflammation or the developement in it of hyda- 
ted vesicles. — 



178 THE OVARIES. 

The Round Ligaments 

Which have already been mentioned, are cords of a fibrous 
structure, with many blood-vessels in them. They arise from 
the uterus below the origin of the Fallopian tubes, and proceed 
under the anterior lamina of the broad ligaments to the abdomi- 
nal rings through which they pass; and then the fibres and ves- 
sels are expanded upon the contiguous cellular substance of the 
mons veneris and labia externa. 

The Ovaries, {Testes Muliebres,) 

Are two bodies of a flattened oval form ; one of which is situ- 
ated on each side of the uterus on the posterior surface of the 
broad ligament, and invested completely by a process of the pos- 
terior lamen, which forms a coat, and also a ligament for it. 
The size of this organ varies in different subjects, but in a major- 
ity of those who are about the age of maturity, it is between ten 
and twelve lines in length. It is connected to the uterus by a 
small ligament (called ovarian) or bundle of fibres of the same 
structure with the round ligaments, which is not more than two 
lines in diameter, and is included between the lamina of the 
broad ligament. 

The process of the broad ligament forms an external serous 
coat to the ovary ; within this is the proper coat of the organ, 
(tunica albuginea,) which is a firm membrane. This membrane 
is so firmly connected to the substance of the ovary which it 
encloses, that it cannot be easily separated from it. The ovary 
is of a whitish colour and soft texture, and has many blood- 
vessels. In virgins of mature age it contains from ten to twenty 
vesicles, formed of a delicate membrane, filled with a transpa- 
rent coagulable fluid. Some of these vesicles are situated so 
near to the surface of the ovary, that they are prominent on its 
surface; others are near the centre. They are very different in 
size ; the largest being between two and three lines in diame- 
ter, and others not more than one-third of that size. 

In women who have had children, or in whom conception has 



VESICUL.E GRAAFIAN^. 



179 

taken place, some of these vesicles are removed, and in their 
place a cicatrix is found. 

It has been ascertained, that during the sexual intercourse with 
males, one of these vesicles, which was protuberant on the sur- 
face, is often ruptured, and a cavity is found. A cicatrix is soon 
formed, where the membrane was ruptured; and in the place 
occupied by the vesicle there is a yellow substance denominated 
Corpus Luteum. This corpus luteum generally continues until 
the middle of pregnancy : it often remains during that state, and 
for some time after delivery, but it gradually vanishes. The 
cicatrization continues during life. 

In many cases these cicatrices correspond with the number 
of conceptions which have taken place; but they often exceed 
the number of conceptions, and they have been found in cases 
where conception has not been known to have taken place. 

In very old subjects, where conception has never taken place, 
the vesicles are either entirely removed, or small dense tubercles 
only remain in their place. 

— These vesicles have been called theova or vesiculce Graafian^, 
in honour of Regnier De Graaf, who described them with care, 
though their existence had been previously pointed out by Vesa- 
lius and Fallopius. 

— These vesicles, as they increase in size at the approach of 
puberty, or from the effect of sexual excitation, make their way 
gradually to the surface of the ovary. In two instances where 
death had occurred under peculiar circumstances, I have seen 
vesicles of the largest size seated as it were, in a little cup-like 
depression of the ovary, with the peritoneal lining raised in relief 
above them. A slight blush of inflammation could be seen on the 
walls of the vesicles, through the peritoneum, which corresponds 
with the description given by De Graaf, of the first stages of con- 
ception in the cow. One of these ovaries I steeped in boiling 
water, and found the vesicles it contained, the largest of which 
was about three lines in diameter, to consist of two membranes, 
separable from each other, the inner one containing a limpid 
albuminous fluid, which had been coagulated by the heat. 
Within these vesicles, after fecundation, according to De Graaf, 



JgQ VESSELS OF THE UTERUS. 

Prevost, Dumas, etc., are developed smaller ones, which are 
the proper ovula Graajiana. These constitute the proper germ 
or ovum, which finally escapes by the laceration of the walls 
of the outer vesicle, and is taken up by the prehensile action of 
the Fallopian tube. The lacerated walls of the outer vesicle, 
give issue to some blood, secrete a yellowish fluid, and thus con- 
stitute the corpus luteum. — 

The Arteries 

Of the uterus are derived from two very different sources ; 
namely, from the spermatic and from the hypogastric arteries. 

The spermatic arteries, instead of passing directly down to 
the abdominal ring, proceed between the lamina of the broad 
ligament, and send branches to the ovaries, which may some- 
times be traced to the vesicles. They also send branches to the 
Fallopian tubes and to the uterus. Those which are on the oppo- 
site sides of the uterus anastomose with each other, and also 
with the branches of the hypogastric arteries. There are also 
branches of these arteries in the round ligaments which accom- 
pany them to their termination outside of the abdominal ring. 

The principal arteries of the uterus are those derived from the 
hypogastric, which sends to each side of it a considerable branch, 
called the Uterine. This vessel leaves the hypogastric very near 
the origin of the internal pudic, and proceeds to the cervix 
of the uterus: it passes between the lamina of the broad liga- 
ments, and sends branches to the edge of the uterus, which pene- 
trate its texture. The branches which are in the texture of the 
uterus are very small, indeed, in young subjects. In women 
who have had children, they are considerably larger; but 
during pregnancy they gradually enlarge with the growth of 
the uterus, and become very considerable. These arteries ob- 
serve a serpentine and peculiarly tortuous course. Those on the 
opposite sides anastomose with each other. 

The Veins 

Of the uterus, like the arteries, form spermatic and uterine 
trunks. The spermatic vein is much larger than the artery. 



BLADDER AND URETHRA. jgj 

It ramifies, as in males, and forms, a very large plexus, which 
constitutes the corpus pampiniforme. Many of the veins which 
form this hody, originate near the ovary: a considerable number 
also come from the Fallopian tubes and the uterus. The sper- 
matic vein and its branches are greatly enlarged indeed during 
pregnancy ; and it is said that they are enlarged the same way 
during the menstrual discharge. 

The most important veins of the uterus are the branches of 
the Uterine Veins. They are extremely numerous, and form a 
plexus on the side of the uterus ; from which two or more 
uterine veins proceed in the course of the artery, and join the 
hypogastric. These veins also are greatly enlarged during 
pregnancy. Some of these are so large as to receive the end 
of the little finger, and are called uterine sinuses, though impro- 
perly. 

The Lymphatic Vessels 
Of the uterus, and its appendages, are very numerous. In the 
unimpregnated state they are small; but during pregnancy they 
increase greatly. They proceed from the uterus in very different 
directions. Some that accompany the round ligaments go to the 
lymphatic gland of the groin. Others, which take the course of 
the uterine blood-vessels, pass to glands in the pelvis, and a third 
set follows the spermatic arteries and veins to the glands of the 
loins. 

The Nerves 
Of the ovaries are derived from the renal plexus, and those of 
the uterus and vagina from the hypogastric plexus, or the lower 
portions of the sympathetic, and the third and fourth sacral 
nerves. 

Of the Bladder and Urethra. 

The situation of the Bladder, as respects the symphysis pubis, 
is nearly alike in both sexes ; but that part of it which is imme- 
diately behind the insertion of the uterus is rather lower in males 
than in females. The bottom of the bladder rests upon the 

VOL. II. 16 



Ig2 URETHRA. 

upper part of the vagina, a thin stratum of cellular substance 
intervening: when that viscus is distended it forms a tumour 
which compresses the vagina. 

The ureters are inserted, and the urethra commences in the 
same part of the bladder, in both sexes. 

The length of the Urethra is between one and two inches. 
When the body is in an erect position, it is nearly horizontal ; 
but it is slightly curved, with its convexity downwards. It is 
immediately above the vagina, and it passes below the body of 
the clitoris. The external orifice is rather more than an inch 
within the glans or head of the clitoris. This orifice is some- 
what prominent in the vagina. 

— In young persons, the external orifice of the urethra is im- 
mediately below the symphysis of the pubis, and nearly level 
with the anterior face of that bone. 

— In women who have borne many children, the urethra is re- 
tracted or shortened, so as to be rarely more than an inch in 
length, and the orifice will be found behind the pubis, near its 
posterior face. A knowledge of these facts will render the in- 
troduction of the catheter in many cases more easy. — 

In the internal lining membrane of the urethra there are many 
orifices of mucous follicles, and also longitudinal wrinkles, as in 
the urethra of males. The diameter of the female urethra and 
its orifice in the bladder are larger than they are in the male. 
For this reason it has been supposed, that women are less liable 
to calculus of the bladder than men.* 

The urethra is intimately connected with the external coat of 
the vagina, and between them there is a spongy cellular substance 
which makes the rough surface of the vagina prominent ; so that 
the urethra has been supposed, although erroneously, to be in- 
vested with the prostate. It is capable of great artificial dilata- 
tion. Its diameter in the natural state is about a quarter of an 
inch. 

* It has, however, been asserted that they are also less liable to calculi in the 

kidneys. 



GENERAL CHANGES IN THE UTERUS. jg3 

Of the Changes induced in the Uterus in the progress of 
Pregnancy. 

The alteration which takes place in the size of the uterus dur- 
ing pregnancy is truly great. About the conclusion of that pe- 
riod, instead of the small body above described, which is almost 
solid, the uterus forms an immense sac, which extends from the 
termination of the vagina in the pelvis, into the epigastric region, 
and from one side of the abdomen to the other ; preserving, 
however, an ovoid figure. 

This change is so gradual at first, that the uterus does not ex- 
tend beyond the cavity of the pelvis before the third month, 
although at the end of the seventh month it is very near the 
epigastric region. 

For the first six months the body of the uterus appears prin- 
cipally concerned in the enlargement: after this the cervix begins 
to change, and is gradually altered so as to compose a portion 
of the sac, of rather less thickness than the rest of the uterus ; 
the mouth being ultimately an aperture in a part which is much 
thinner than the other portions of the organ. 

The change which takes place in the texture of some of the 
appendages of the uterus is very important. 

The Broad Ligaments, which seem particularly calculated to 
favour the extension of the uterus, are necessarily altered by the 
change in the size of that organ, but not entirely done away. 
The portion of peritoneum of which they are formed must be 
very much enlarged with the growth of the uterus, as it con- 
tinues to cover it- The Round Ligaments are much elongated ; 
and they observe a more straight course to the abdominal ring. 
The Fallopian Tubes are enlarged ; and instead of passing off 
laterally from the uterus, they now proceed downwards by the 
side of it. The Ovaries appear rather larger and more spongy : 
their relative situation is necessarily lower. 

The change in the Uterus itself is particularly interesting. The 
great increase of its size is not attended with any considerable 
diminution of thickness in its substance; nor are the arteries 
much less convoluted than before pregnancy, as might have been 



184 GENERAL OBSERVATIONS. 

expected. They are greatly enlarged in diameter, and the ori- 
fices of the exhalent vessels on the internal surface of the uterus 
are much more perceptible. 

The veins are much more enlarged than the arteries, and in 
some places appear more than half an inch in diameter. They 
are not regularly cylindrical, but rather flat. They anastomose 
so as to form an irregular net-work. 

The uterus appears much more fibrous and muscular in the 
gravid than in the unimpregnated state. The contractile power 
of the gravid uterus is not only proved by the expulsion of its 
contents, but also by very vigorous contractions, which are oc- 
casionally observed by accoucheurs. 

Although the general effects which result from the particular conditions of 
the uterus in pregnancy, menstruation, &c, evince that the influence of 
this organ upon the whole system is very great, yet it seems probable that 
the sexual peculiarities of females are especially dependent upon the 
ovaria. 

This sentiment is confirmed by an account of a woman in whom the ovaria 
were deficient, which is published in the London Philosophical Transactions 
for 1805, by Mr. C. Pears. The subject lived to the age of twenty-nine 
years. She ceased to grow after the age of ten years, and therefore was 
not more than four feet six inches in height : her breadth across the hips 
was but nine inches, although the breadth of the shoulders was fourteen. 
Her breast and nipples were never enlarged more than they are in the male 
subject. There was no hair on the pubes, nor were there any indications of 
puberty in mind or body. She never menstruated. At the age of twenty- 
nine she died of a complaint in the breast, attended with convulsions. 
The uterus and os tincae were found not increased beyond their usual size 
during infancy. The cavity of the uterus was of the common shape, 
but its coats were membranous. The Fallopian tubes were pervious. 
" The Ovaria were so indistinct that they rather showed the rudiments 
which ought to have formed them, than any part of the natural struc- 
ture." 

Another case, which confirms the aforesaid sentiment, is related in one of 
the French periodical publications. 

It has been long known that a race of savages near the Cape of Good Hope 
were distinguished from the generality of their species by a peculiarity 
about the pudendum. An account of this structure has been given with 
some precision by Messrs. Peron and Lesueur, in a paper which was read 
to the National Institute of France. It is a flap or apron, four inches in 



PECULIARITIES IN THE ABDOMEN OF THE FOETUS. jg5 

length, which is united to the external labia near their upper angle, and 
hangs down before the clitoris and the external orifice of the parts of ge- 
neration. It is divided below into two lobes, which cover the orifice. It 
is formed by a soft distensible skin, free from hair, which is occasionally 
corrugated like the scrotum, and is rather more florid than the ordinary 
cutis.* — This is the tablier, or mere natural enlargement of the 
nymphse, common to the females of some races of men. — 

The Abdomen of the Fatus. 

The difference between the foetus and the adult, in the cavity 
of the abdomen, is very conspicuous at the first view. 

The Liver in the foetus is so large that it occupies a very con- 
siderable part of the abdomen. Its left lobe, which is larger in 
proportion than the right, extends far into the left hypochondriac 
region. 

The Bladder of urine, when filled, extends from the cavity of 
the pelvis a considerable distance towards the umbilicus: so that 
the greatest part of it is in the cavity of the abdomen. A liga- 
ment of a conical figure extends from the centre of the upper 
part of the bladder to the umbilicus, with an artery on each side 
of it, which is soon to be described. This ligament, which is 
in the situation of the urachus of the foetus of quadrupeds, is 
hollow, and thus frequently forms a canal, which has a verv 
small diameter, that communicates with the bladder by an 
aperture still smaller, and continues a short distance from the 
bladder towards the umbilicus. In a few rare instances, this 
canal has extended to the umbilicus, so that urine has been dis- 
charged through it, but the ligament is commonly solid there. 

The Stomach appears to be more curved in the foetus than in 
the adult. 

The Great Intestine does not extend sufficiently far, beyond 
the insertion of the ileon, to form the caecum completely. 

The Glandules Renales are much larger in proportion in the 

* This paper has not yet been published by the Institute, but it is referred to by 
M. Cuvier in his Lecons d'Anatomie Comparee, vol. v. page 124. — Messrs. Peron 
and Lesueur were naturalists who accompanied captain Baudin in his voyage of 
discovery ; the latter has been for some years resident in Philadelphia. 

16 * 



] 86 DESCENT OF THE TESTICLE OF THE FCETUS. 

foetus lhan in the adult. The colour of the fluid they contain is 
more florid. 

The Kidneys are lobulated. 

The Testicles in the foetus are found above the pelvis, in the 
lumbar region, behind the peritoneum, until two months before 
birth. Thus situated, their blood-vessels and nerves proceed 
from sources which are near them ; but the vas deferens, being 
connected to the vesiculse seminales by one extremity, is neces- 
sarily in a very different situation from what it is in the adult : 
it proceeds from the testicle downwards to the neck of the blad- 
der. While each testicle is in this situation, it is connected with 
a substance or ligament, called Gubemaculum, of a conical or 
pyramidical form, which is attached to its lower end, and extends 
from it to the abdominal ring. This substance is vascular, and 
of a fibrous texture: its large extremity adheres to the testicle, 
its lower and small extremity passes through the abdominal ring, 
and appears to terminate in the cellular substance exterior to 
that opening, like the round ligament in females. The Guber- 
naculum, as well as the testicle, is behind the peritoneum ; and 
the peritoneum adheres to each of them more firmly than it does 
to any of the surrounding parts. It seems that, by the contrac- 
tion of the Gubemaculum, the testicle is moved down from its 
original situation to the abdominal ring, and through the abdo- 
minal ring into the scrotum. The peritoneum, which adheres 
firmly to the gubemaculum and testicle, and is loosely connected 
to the other parts, yields to this operation ; and when the testicle 
has arrived near the abdominal ring, a portion of the peritoneum 
is protruded a little way before it into the scrotum : forming a 
cavity like the finger of a glove. The testicle passes down be- 
hind this process of the peritoneum, and is covered by it as it 
was in the abdomen. Although it appears protruded into the 
cavity, it is exterior to it, and behind it ; and the vessels, &c. 
which belong to the testicle are also exterior to it. 

The cavity formed in the scrotum, by this process of the peri- 
toneum, necessarily communicates with the cavity of the abdo- 
men at its formation; but very soon after the testicle has 
descended into the scrotum, the upper part of this cavity is closed 



UMBILICAL VESSELS. 



187 




up, while the lower part of the process Fig. 65. 

continues unchanged, and constitutes 
the Tunica Vaginalis Testis. In some 
instances the upper part of this process 
does not close up, and the communica- 
tion with the cavity of the abdomen 
continues. The descent of the intes- 
tine into the cavity thus circumstanced, 
constitutes that species of hernia which 
is denominated Congenital.^ 

The most important peculiarities in 
the abdomen of the fetus are those 
connected with the circulation of the 
blood. 

The internal iliac or hypogastric 
arteries are larger than the external 
iliacs. Their main trunks are continued 
on each side of the bladder to its fun- 
dus, and proceed from it, with the lig- 
ament, to the umbilicus; when they pass out of the abdomen to 
go along the umbilical cord to the placenta. These arteries are 
now denominated the Umbilical, and are very considerable in 

• Diagram of the circulation in the human foetus. 1, 1, Umbilical arteries. 
2, Umbilical vein. The blood of the umbilical vein is partly distributed to the 
liver, in the right tube of which it becomes mixed with the blood of the porta, and 
in part passes directly by the ductus venosus 3, to the vena cava inferior, 4. 5, 
Venae cuvee hepaticae. 6, Superior cava. 7, Right auricle. 8, Pulmonary veins. 9, 
Left auricle. 10, Left ventricle. 11, Ascending aorta or left arch of the aorta. 
12, Vessels to the head and upper extremities. 13, Right ventricle. 14, Ductus 
arteriosus, or right aortic arch. 15, Descending aorta. — p. 

t These interesting circumstances respecting the original situation of the testi- 
cle, and its descent into the scrotum, were discovered and elucidated by Haller, 
Hunter, Pott, Camper, and several other very respectable anatomists and surgeons. 
There is, however, a difference of opinion between some of them, as to the time 
when the testicle leaves the abdomen. Haller thought the testicles were seldom 
in the scrotum at birth. Hunter and Camper found them so generally. 

It has been suggested that there are some national peculiarities in this respect ; 
that amongst the Hungarians, for example, the testicles often remain above the ab- 
dominal ring until near the age of puberty. 

The student will find an interesting description of the situation of the testis, 
and its descent in the foetus, in the " Observations on certain parts of the Animal 
Economy," by John Hunter. 



J 88 UMBILICAL VESSELS. 

size. After birth, as there is no circulation in them, they soon 
begin to change: their cavity becomes gradually obliterated, 
and they are converted into ligaments. They are exterior to the 
peritoneum, and contained in a duplicature of it. 

A vein also called the Umbilical, which is much larger in di- 
ameter than both of the arteries, returns from the placenta along 
the cord, and enters the cavity of the abdomen at the umbilicus. 
It proceeds thence, exterior to the peritoneum, but in a duplicature 
of it called the Falciform Ligament, to the liver, and enters that 
viscus at the great fissure ; along which it passes to the left 
branch of the sinus of the vena portarum, into which it opens 
and discharges the blood which flows through it from the pla- 
centa. It opens on the anterior side of the branch of the vena 
portarum, and from the posterior side of the branch, opposite to 
this opening, proceeds a duct or canal, which opens into the left 
hepatic vein near its junction with the vena cava. This com- 
municating vessel is called the Ductus, or Canalis Venosus ; to 
distinguish it from the duct which passes from the pulmonary 
artery to the aorta, and is called Ductus, or Canalis Arteriosus. 
This venous duct carries some of the blood of the umbilical vein 
directly to the vena cava; but it is much smaller than the umbi- 
lical vein, and of course a considerable quantity of the blood 
which passes through the umbilical vein must pass through the 
liver, by the vena portarum, before it can enter the cava. 

In some fetal subjects, if a probe of sufficient length be intro- 
duced within the umbilical vein and pushed forwards, it will pass 
to the heart, without much difficulty or opposition, as if it pro- 
ceeded along one continued tube, although it really passes from 
the umbilical vein across the branch of the vena portarum, and 
then through the ductus venosus, and through a portion of the 
left hepatic vein, into the inferior vena cava. 

If the umbilical vein be injected with a composition, which 
will be firm when cool, it appears to terminate in a rounded end, 
which is situated in the transverse fissure of the liver : the sinus 
of the vena portarum, into which this vein enters, appears like 
two branches going off, one from each side of it, and the ductus 
venosus like a branch continuing in the direction of the main 
trunk of the umbilical vein. 



UMBILICAL VESSELS. i oq 

The umbilical vein, in its progress through the fissure of the 
liver, before it arrives at the sinus of the vena portarum, sends 
off a considerable number of branches to each of the lobes of 
that organ, but more to the left than to the right lobe. 

After birth, when blood ceases to flow through the umbilical 
vein, it is gradually converted into a ligament; and the venous 
duct is also converted into a ligament in the same manner. The 
vena portarum, which before appeared very small, when com- 
pared with the umbilical vein, now brings all the blood which 
fills its great sinus, and increases considerably in size. 

It has been ascertained by anatomical investigation, that the 
umbilical arteries above mentioned, after ramifying minutely in 
the placenta, communicate with the minute branches of the 
umbilical vein ; and it is probable that the whole blood carried 
to the placenta by these arteries, returns by the umbilical vein 
to the foetus. 

It is clearly proved by the effects of pressure on the umbilical 
cord, in cases of delivery by the feet, as well as by other similar 
circumstances, that this circulation cannot be suspended for any 
length of time without destroying the life of the foetus. From 
these circumstances, and from the florid colour which the blood 
acquires by circulating in the placenta, it seems probable that the 
object of the circulation through that organ is somewhat analo- 
gous to the object of the pulmonary circulation through the lungs 
of adults.* 

• During the first four months of pregnancy a very small vesicle, which does 
not exceed the size of a pea, is found between the chorion and the amnios, near the 
insertion of the umbilical cord into the placenta. It is connected to the fcetus by 
an artery and a vein, which pass from the abdomen through the umbilicus, and 
proceeding along the cord to the placenta, continue from it to the vesicle. The 
artery arises from the mesenteric, and the vein is united to the mesenteric branch 
of the vena portarum. It is probable that these vessels commonly exist no longer 
than the vesicle, namely, about four months ; but they have been seen by Haller 
and Chaussier at the termination of pregnancy. They are called Omphato-Mesen. 
teric vessels. The vesicle is denominated the Umbilical Vesicle. 

This inexplicable structure is delineated in Hunter's Anatomy of the Gravid 
Uterus, plate xxxiii. figures v. and vi. ; in the Academical Annotations of Albinus, 
first book, plate i. figure xii.; and also in the Icones Embryonum Humanorum of 
Soemmering, figure ii. 



PART VIII. 

GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 
CHAPTER VII. 

OF THE BLOOD-VESSELS IN GENERAL. GENERAL ANATOMY OF THE 
ARTERIAL SYSTEM. GENERAL REMARKS UPON THE HEART. GE- 
NERAL ANATOMY OF THE VENOUS SYSTEM. 

Of the Blood-vessels in General. 

The blood-vessels are flexible tubes, of a peculiar texture, 
through which blood passes from the heart to the different parts 
of the body, and returns again from these parts to the heart. 
They are to be found, in varying proportions, in almost every part 
of the body, and seem to enter into its texture. 

The tubes which carry blood from the heart, are more sub- 
stantial and more elastic than those through which it returns to 
the heart. They are generally found empty after death ; and, 
therefore, were called Arteries by the ancient anatomists, who 
supposed that they carried air, and not blood. 

The tubes which return the blood to the heart are denominated 
Veins. They are less substantial and less elastic than arteries, 
and are generally full of blood in the dead subject. 

There are two great arteries, from which all the other arterial 
vessels of the body are derived. They are very justly compared 
to the trunks of trees, and the smaller vessels to their branches. 
One of these great arteries, called the Aorta, carries blood to 
every part of the body. The other great vessel, called the Pul- 
monary Artery, carries blood exclusively to the lungs. 

The veins which correspond to the branches of the Aorta, 
unite to each other, so as to form the two great trunks that 
proceed to the heart. One of these trunks, coming from the 
superior parts of the body, is called the Superior, or Descending 



t 



OF THE BLOOD-VESSELS IN GENERAL. jgj 

Vena Cava. The other, which comes from the lower parts of 
the body, is called the Inferior, or Ascending Vena Cava. 

The veins which correspond with the branches of the Pul- 
monary Artery, and return to the heart the blood of the lungs, 
are four in number ; two of them proceeding from each lung. 
They are called Pulmonary Veins. 

In many of the veins there are valves which prevent the blood 
they contain from moving towards the surface and extremities 
of the body, but allow it to pass towards the heart without im- 
pediment. 

From the construction Fig. 66.* 

ofthecavitiesof the heart, a 

and the position of the 
valves which are in them' 
as well as the situation of 
the valves at the com- 
mencement of the great e 
arteries, and the above 
mentioned valves of the 
veins, it is evident, that a .... 
when the blood circulates, b — 
it must move from the 
heart, through the aorta 
and its branches, to the 

different parts of the body, c 

and return from these 

parts through the vena? '^^MMi y M 

cavae, to the heart; that, 

when deposited in the heart by the venae cavae, it must proceed 

through the pulmonary artery to the lungs, and return from the 

lungs through the pulmonary veins to the heart, in order to pass 

again from that organ into the aorta. 




* Fig. 66. Trunk of a large vein, laid open in order to exhibit the valves, formed 
by doublings of the internal lining membrane, a, Superior portion of the vein, or 
that towards the heart, b, Valves, the concavity of which is directed towards the 
heart, c, Branches of the veins, anastomosing together, and uniting to form a 
large branch d, which opens into (he principal trunk at e. — p. 



192 OF THE SANGUIFEROUS SYSTEM. 

It is also certain, that the blood is forced from the heart into 
the arteries, by the contraction of the muscular fibres of which 
the heart is composed; and that the blood-vessels likewise per- 
form a part in the circulation, they propelling the blood which 
is thus thrown into them: but their action appears to depend upon 
causes of a complex nature. 

General Anatomy of the Arterial System. 

The arteries are so much concerned in the important function 
of the circulation of the blood, that every circumstance connected 
with them is very interesting. 

They are composed of coats or tunics, which are very elastic 
and strong, and which are also very thick. In consequence of 
the firmness of their coats, they continue open, after their con- 
tents are discharged, like hard tubes. They submit to great 
dilatation, and elongation, when fluids are forced into them, and 
return to their former dimensions when the distending cause is 
withdrawn. This elasticity is particularly subservient to the 
circulation of the blood. It admits the artery to distend readily, 
and receive the blood which is thrown into it by the contraction 
of the heart. It also produces the contraction of the artery; 
which takes place as soon as the action of the heart ceases; and 
this contraction of the heart necessarily forces the blood for- 
ward, as the valves at its orifice prevent it from returning to the 
heart. 

The motion of the artery, which is so easily perceived by the 
touch, and in many instances also by the eye, is completely ex- 
plained by the discharge of blood into the artery from the heart, 
and by the elasticity of the vessel, by which it reacts upon the 
blood. In some cases it is not simply the diameter of the artery 
which is enlarged, but a portion of the vessel is elongated ; and 
this elongation, by producing a curvature of it, renders its motion 
more visible. 

In the aorta, and probably in its large branches Elasticity 
seems to be the principal cause of the continuance of the motion 
which is originally given to the blood by the heart. But there 
are many circumstances connected with the smaller vessels, 



STRUCTURE OF THE ARTERIES. 193 

which evince that they exert a power which is very different 
indeed from elasticity. Thus, the application of local stimulants 
or rubefacients, and of heat, is followed by an increase of motion 
in the arteries of the parts to which they are applied. Neither 
of these causes could produce their effect by the influence of 
elasticity : but the effect of these and other similar causes is 
uniformly produced ; and a power of independent motion, or 
Irritability, is thus proved to exist in these vessels, and seems 
essentially necessary to the circulation of the blood. 

The Structure of the Arteries 

Is, therefore, a subject of importance, and has received a 
considerable degree of attention from anatomists. 

They are composed of a dense elastic substance, of a whitish 
colour. Their external surface is rough, and intimately con- 
nected with the cellular membrane, which every where surrounds 
it in varying quantities. Internally, they are lined with a thin 
membrane, which is very smooth and flexible, and is also very 
elastic. The substance which composes the artery, and is situ- 
ated between the cellular investment and the internal membrane, 
consists of fibres, which are nearly, though not completely cir- 
cular, but so arranged as to constitute a cylinder. These fibres 
may be separated from each other so as to form lamina, which 
have been considered as different coats of the arteries; but there 
is no arrangement of them which composes regular distinct 
strata. The coats of arteries may, therefore, be separated into 
a greater or smaller number of lamina, according to the thickness 
of these lamina. 

The fibres which compose these lamina appear to be united to 
each other in a way which readily allows of their separation, at 
the same time that they form a firm texture. Although arteries 
thus appear essentially different from muscles in their hardness 
and their elasticity, as well as in their general texture, they are 
considered, by a great majority of anatomists, as partaking 
more or less of a muscular structure. 

In the human subject their structure is very difficult of demon- 
stration, and great differences exist in the accounts which are 

VOL. II. 17 



194 QUESTIONS RESPECTING THE MUSCULARITY OF ARTERIES. 

given of it, even by anatomists who agree in the general senti- 
ment that the arteries are muscular. 

Thus, Haller believed that muscular fibres were most abun- 
dant in the large arteries, while J. Hunter thought the reverse. 

Hunter appears to have investigated this subject with great 
attention, and supposed the muscular substance, in the composi- 
tion of arteries, to be interior, and the elastic matter exterior; 
that in large arteries this muscular substance is very small in 
quantity, and gradually increases in proportion as the artery 
diminishes in size. He, however, observes, that he never could 
discover the direction of the muscular fibres.* 

When the great talents of Mr. Hunter as an anatomist are 
considered, this circumstance cannot fail to excite a belief that 
the existence of these fibres is not certain : and if to this be 
added the fact, that even the red-coloured substance of the arte- 
ries is elastic, and in that respect different from muscular sub- 
stance, the reasons for doubting must be increased. 

Bichat appears to have entertained very strong doubts on the 
subject; but he stands almost alone; for a large number both 
of the preceding and contemporary anatomists, seem to have 
adopted the sentiment, that the arteries have a muscular structure. 

The student of anatomy can very easily examine this subject 
himself, by separating the coats of arteries into different lamina ; 
and by viewing the edges of the transverse and longitudinal sec- 
tions of those vessels. While thus engaged with this question, 
he will read with great advantage what has been written upon it 
by Mr. Hunter, in his treatise on the blood, &c, (see chapter 
second, section 3.) Bichat ought also to be read upon this sub- 
ject, which he has discussed in his Amatomie Generale — Systeme 
Vasculaire a Sang Rouge, article Troisieme, &c. ; and also in his 
Traite des Membranes, article Sixieme. 

The belief of the irritability of arteries does not, however, rest 
upon the appearance of their fibres. 

1. It is asserted by very respectable authors,f that they have 

* Treatise on the Blood, &c. vol. i. p. 113. Bradford's edition. 
t See Soemmering on the Structure of the Human Body, vol. iv. German edi- 
tion. Dr. Jones on the Process employed by nature for suppressing Hemorrhage, &c. 



PROOFS OF THE IRRITABILITY OF THE ARTERIES. jgej 

been made to contract by the application of mechanical and of 
chemical irritation, and also of the electric and galvanic power. 

2. A partial or local action of arteries is often produced by the 
local application of heat and rubefacients, as has been already 
observed. 

3. Arterial action is often suspended in a particular part by 
the application of cold. It has also been observed that the arte- 
ries have for a short time ceased to pulsate in cases of extreme 
contusion and laceration of the limbs.* 

4. When arteries are divided transversely in living animals, 
they often contract so as to close completely the orifice made by 
the division. 

5. In a horse, bled to death, it was ascertained by Mr. Hunter, 
that the transverse diameter of the arteries was diminished to a 
degree that could not be explained by their elasticity. He also 
found that, after death, the arteries, especially those of the smaller 
size, are generally in a state of contraction, which is greater than 
can be explained by their elasticity: for if they are distended 
mechanically, they do not contract again to their former size, 
but continue of a larger diameter than they were before the dis- 
tention; although their elasticity may act so as to restore a very 
considerable degree of the contraction observed at death. 

The contraction, which is thus, done away by distention, Mr. 
Hunter supposed to have been produced by muscular fibres : for 
if it had been dependent on elasticity, it must have reappeared 
when the distending power was withdrawn. 

It therefore seems certain, that the arteries have a power of 
contraction different from that which depends upon elasticity ; 
but whether this depend upon muscular fibres superadded to 
them, or upon an irritable quality in the ordinary elastic fibres of 
blood-vessels, is a question which is not perhaps completely de- 
cided. 

— The middle coat of the arteries is composed of flat fibres 
and bundles of fibres, which surround the vessel in a circular di- 

* This local suspension of arterial motion by cold, &c. applied locally, is very 
difficult to explain : as the action of the heart and the elasticity of the arteries ap- 
pear sufficient to account for the pulsation of the large arteries. 



196 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

rection. They are now generally believed to be not muscular 
in their structure, and do not exist in veins. In the ox and the 
elephant, they are particularly well developed, in both of which 
I have examined them with attention, but without discovering 
any evidence of muscularity in their composition. Berzelius has 
shown that the fibres of the elastic coats of the arteries differ 
chemically from those of the muscles. Muscular substance is soft 
and lax, and contains nearly three-fourths its weight of water, and 
has the same chemical properties as the fibrine of the blood. The 
substance of the arterial coat is dry and contains no fibrine, and 
Dr. Hodgkin has observed that its fibres do not present the 
transverse striae seen on the muscular fibre. The arteries are 
eminently elastic, and to this they owe their property of con- 
traction, when they have been distended, beyond the usual di- 
mensions. It is by virtue of this elasticity also, that the arteries 
retain their tubular form after death, when they are emptied of 
blood. The reaction of this coat during the intervals of the 
heart's action, also contributes to render the flow of blood more 
uniform. — * 

The motion of the blood in the arteries appears to depend, 

1st, Upon the impulse given to it by the action of the heart. 

2dly, Upon the elasticity of the arteries, in consequence of 
which they first give way to the blood impelled into them, and 
then react upon it ; and 

3dly, Upon the power of contraction in the arteries, or their 
irritability. 

In the larger arteries the blood seems to move as it would 
through an inanimate elastic tube, in consequence of the impulse 
given by the heart, and kept up by the arteries themselves. In 
the smaller vessels it seems probable that the motion of the blood 
depends in a considerable degree upon the contraction which 
arises from their irritability. 

The obvious effect of the elasticity of the arteries is to resist 
distention and elongation, and to contract the artery to its natu- 
ral state, when the distending or elongating cause ceases to act. 
But it must also resist the contraction induced by the muscular 

* Weber's Hildebrandt's Anatomie, tome iii. p. 68.— p. 



GENERAL OBSERVATIONS ON THE ARTERIES. jg-j 

fibres, and restore the artery to its natural size when the muscu- 
lar fibres cease to act after contracting it, as has been observed 
by Mr. Hunter. 

It seems probable that all the fibres of which the artery con- 
sists are nearly, but not completely circular ; for it is not certain 
that there are any longitudinal fibres in the structure of an 
artery. 

The internal coat of these vessels is very smooth, but ex- 
tremely dense and firm; and seems to be rendered moist and 
flexible by an exudation on its surface. It adheres very closely 
to the contiguous fibres of the coat exterior to it, but may be 
very readily peeled off from them. It is of a whitish colour, 
and, like the fibrous structure of the artery, is very elastic. Like 
that substance, also, it is easily torn or broken ; and when liga- 
tures have been applied to arteries, it has often been observed 
that the fibrous structure, and the internal coat have been sepa- 
rated while this external cellular coat has remained entire. 

The arteries are supplied with their proper blood-vessels and 
lymphatics, (vasa vasorum.) It is to be observed, that these blood- 
vessels are not derived from the artery on which they run, but 
from the contiguous vessels. 

These vessels have nerves also, which are rather small in size, 
when compared with those which go to other parts. 

Arteries appear to have a cylindrical form, for no diminution 
of diameter is observable in those portions of them which send 
off no ramifications. 

When an artery ramifies, the area of the different branches 
exceeds considerably that of the main trunk. Upon this princi- 
ple, the aorta and its branches have been compared to a cone, 
the basis of which is formed by the branches, and the apex by 
the trunk.* 

The transverse section of an artery is circular. 

There are no valves in the arteries, except those of the orifices 
of the aorta and the pulmonary artery, at the heart. The valves 

* According to Brussiere the relation of the branches of the aorta to its trunk is 
as 25 to 16; Helvetius reckons the orifice of the aorta in comparison with its 
branches as 64 to 71. Lassus. — h. 

17* 



198 GENERAL ANATOMY" OF THE SANGUIFEROUS SVSTEM. 

of the pulmonary artery have been described in vol. i. p. 463, 
and those of the aorta have an exact resemblance to them, but 
are rather larger. 

The course of the arteries throughout the body is obviously 
calculated to prevent there exposure to pressure, or to great ex- 
tension from the flexure of the articulations by which they pass. 
With this view they sometimes proceed in a winding direction ; 
and when they pass over parts which are subject to great dis- 
tention or enlargement, as the cheeks, they often meander; and, 
therefore, their length may be increased by straightening, with- 
out stretching them. 

Their course appears sometimes to have been calculated to 
lessen the force of the blood, as is the case with the Internal Caro- 
tid and the Vertebral arteries. 

In the trunk of the body the branches of arteries generally 
form obtuse angles with the trunks from which they proceed. In 
the limbs these angles are acute. 

The communication of arteries with each other is termed 
Anastomosis. In some instances, two branches which proceed 
in a course nearly similar, unite with an acute angle, and form 
one common trunk. Sometimes a transverse branch runs from 
one to the other, so as to form a right angle with each. In 
other cases, the two anastomosing branches form an arch, or 
portion of a circle, from which many branches go off. 

By successive ramifications, arteries gradually diminish in 
size, until they are finally extremely small. 

The small arteries do not carry red blood, their diameters 
being smaller than those of the red particles of that fluid, the 
serous or aqueous part of the blood can, therefore, only pass 
through them. 

Many of the arteries which carry red blood, and of the last 
mentioned serous arteries, terminate in veins, which are in some 
respects, a continuation of the tube reflected backwards.* 

* Malpighi and Leuenhoek declare, that by the aid of a microscope they have 
seen arteries terminating in the veins. Haller advances formally his own experi- 
ence in support of his assertion. Other anatomists have seen, that in blowing into 
an artery, the air passed into the corresponding veins. Nevertheless, Duverney 



GENERAL REMARKS UPON THE HEART. 199 

Position of the Heart. 
— The heart is situated mainly between the sternum and spine; 
its left ventricle is placed immediately behind and to the inner 
side of the left nipple ; its base is horizontal, and nearly opposite 
a line drawn horizontally from the junction of the cartilage of 
the third rib with the sternum. The right auricle is placed so 
that its free border is a little to the right side of the sternum, 
between the junction of the third and fourth costal cartilages 
with that bone. The flattened surface of the heart below, rests 
upon the bottom of the pericardium, covering the cordiform ten- 
don of the diaphragm. The apex of the heart, formed by the 
extremity of the left ventricle, is nearly opposite the junction of 
the fifth rib with its cartilage. 

Dimensions of the Heart. 
— The heart was said by Laennec, to be of the size of the closed 
fist of the same subject. But this is a rule upon which little re- 
liance is to be placed. It was found by very accurate observa- 
tions made by M. Bizot,* on one hundred and fifty-six subjects 
of different ages of life, from one to eighty, that the heart has no 
natural limit in regard to size, but increases indefinitely without 
being diseased, according to the age of the subject. After fifty 
years, however, the growth is so slow, as to be scarcely notice- 
able, except it becomes diseased. 

— In 18 subjects between the ages of 16 and 29, on the average, 
the length was 42 lines; breadth 46; thickness, 17^. In 19, be- 
tween the ages of 50 and 79, the average length was 46 lines; 
breadth 53; thickness 18^. In females upon the average at the 
same ages, the dimensions were each about three lines less. 
The dimensions of the heart are directly in relation to the breadth 
of the shoulders, and by careful observations made upon sixty- 
four subjects, consisting of nearly an equal number of each sex, 

and some others say, that a particular substance is interposed between the extre- 
mities of these vessels. Ruysch, in his Thesauras Anatomicus, VI. No. 73, says, 
in rcplctione arteriarum, replentur et plurimum quosque venae, et vice versa, ita ut 
impossible videatur precise diccre quomodores se habeat. Discours surl'Anat. — h. 
* Mem. dc la Sociele Med. d'Observalion de Paris, 1836. — p. 



200 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

it was found by M. Bizot, that in individuals of middle stature 
and under, that the heart was absolutely of greater size, than in 
those who were distinguished for their tallness. 
— It has been asserted by Andral,* that the four cavities of the 
heart, in their natural and healthy state, are as near as may be 
of equal dimensions ; and by M. Beclard,f that the right ventricle 
as age advances, becomes enlarged in a greater proportion than 
the left. 

— The researches of the same careful observer has shown, that 
the right ventricle as well as right auricle,! an( ^ r '§ nt auriculo- 
ventricular orifice and pulmonary artery, are larger than the 
corresponding parts of the left side, at all the different stages of 
life. The mean dimensions in men, taken from many indivi- 
duals, between the ages of 15 and 79, are — 

Left ventricle, length, 34 lines, breadth, 54 lines. 

Right " 37 " « 82 " 

— Mean thickness of the ventricles between same ages.§ 

Left at base, 4^ lines, middle, 5 lines, near its point, 4 lines. 
Right " 2 nearly, « l£ « « 1 " 

— Mean circumferences of the auriculo-ventricular orifices. 

Of the left, (between the same ages, 16 to 79,) 45§ lines. 
Of the right, " 54 « 

— Mean circumference of the orifice of the aorta, and pul- 
monary arteries, taken opposite the free border of the sigmoid 
valves. 

* Diet, de Med. nouv. ed. lorn. viii. — p. 

t Lieutaud and Sabatier also, thought the cavities of the ventricles were equal 
in the healthy state, and that the cavity of the right was enlarged by the respira- 
tory struggles at the time of death. It has been proved, however, long since, 
by Legallois, that the mode of death has no effect in altering the form of the 
heart. — p. 

t The comparative measurements of the auricles have not been taken. — p. 

§ The thickness of the septum ventriculorum is about the same as that of the 
left ventricle, and undergoes the same modifications in respect to age. The co- 
lumnar carnae are not included in the measurement of the thickness of the ven- 
tricle. — p. 



DIMENSIONS OF THE HEART. 20 1 

Of the aorta, (between the same ages,) 31| lines. 

Of the pulmonary artery, 32^* " 

— The coronary arteries undergo a developement in size, exactly 
in harmony with that of the heart. In the fetus, where the thick- 
ness of both ventricles seems equal, there is no difference in the 
size of the coronary arteries. But as the walls increase in 
thickness, especially that of the left ventricle, these arteries en- 
large, and in particular the left. Boyer, H. Cloquet and others, 
have fallen into error, in stating that the calibre of the left co- 
ronary artery is less than the right. 
— Circumference of the coronary arteries at their origin. 

General mean of the left in man, 5^ lines. 

" " right " 41 " 

— The thickness of the ventricles, which are at birth nearly the 
same, go on increasing, as life advances^ though not in equal 
proportions. The walls of the right ventricle are arrested in the 
healthy state at their maximum of thickness, much sooner than 
those of the left. 

— The volume of the heart, and the greater or less capacity of the 
right ventricle, have, in the healthy state, but little influence over 
the thickness of its walls. Its thickness, however, is found slightly 
increased in advanced age. That of the left ventricle increases 
without cessation. Hence, the assertion of Andral and others, 
that the natural thickness of the walls of the left ventricle is 
three or four times as great as that of the right, is applicable only 
in advanced life. 

— Professor Cruveilhier has asserted, that the thickness of the 
ventricles beyond which only hypertrophy is to be considered as 
existing, are seven to eight lines for the left, and four to five lines 
for the right. The numerous and careful measurements of M. 
Bisot, have, however, proved this standard to be excessive, and 

* In the latter ages of life, the aorta increases in its dimensions so as to exceed 
in its circumference at its orifice, the pulmonary artery. This is in all probability 
owing to the frequency of the morbid alterations of the aorta in old men, in which 
the middle coat of the vessel loses its elasticity and becomes dilated : while altera- 
tions of the pulmonary artery are very rare, even at the most advanced stages of 
life. — p. 



202 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

that a thickness of seven lines of the left ventricles in man, and 

six in women, would be a commencement of hypertrophy, even 

in the last stages of life ; and that the maximum of thickness in 

the right ventricle, from 50 to 79 years, in man is but 2|th lines, 

and but 1^ line in woman. 

— Mean dimensions of the aorta, taken from a large number of 

subjects at seven different points. 

— One line on the cardiac side of the arteria innominata. 

Men. Women. 

General mean of circum- 
ference, from 16 to 79, 33 lines. Do. from 16 to 89, 31 lines. 

Near the left subclavian, 

general mean, 33 " " 24 " 

Opposite the remains of 

the ductus arteriosus, 25 " " 23 " 

Above the cceliac artery, 22| " " 20^ " 

— In all the measurements of the heart and other portions of the 

vascular system, we shall speak only of the healthy or normal 

measurements at the different stages of life. 

Below the renal arteries, 17^ lines. In women, 16 lines. 

Near its bifurcation, 17 " do. 15 " 

— The diameter of the aorta is greater, as will be seen by these 
measurements, both in the male and female, near the origin of 
the innominata, than at its connexion with the heart. It is less 
near the left subclavian, diminishes considerably near the 
coeliac and renal branches, and from thence to its termination, 
scarcely varies at all. These results, also disprove the assertion 
of Richerand, that the descending aorta and iliac arteries,* are 
larger in woman than in man. In woman, the interna] iliacs 
continue to increase in size even after the age at which the 
funciion of reproduction has ceased. In fact, the whole aortic 
trunk, like the heart, continues to increase gradually in size in 
both sexes, up to the most advanced period of life, and like the 
heart also, as it increases in calibre, has the thickness of its walls 
likewise augmented-! 

* See (further on) measurement of iliac. — r. 
t See Richerand's Physiology, 10th edit. 



FORM OF THE ARTERIES. 203 

— The branches of the aorta both in regard to size and age, 
undergo corresponding changes with the aorta itself. Of the 
abdominal branches, the superior mesenteric is the largest of all; 
the next in size are the renal and coeliac ; the two latter being 
nearly of the same size. Hence, each kidney receives as much 
arterial blood as the liver, spleen, and stomach together, as 
would seem to be rendered appropriate by the relative functions 
of the organs ; that of the kidneys being to depurate the blood 
of its saline and many other noxious principles. 
— Of all the organs in the body, the heart and arteries are the 
only ones which constantly increase in dimensions; in old age 
the muscles become atrophied, the skin shrivels, and even the 
skeleton diminishes in bulk. 

Form of the Arteries. 

— Bichat and Richerand have considered every arterial tube 
to be evenly cylindrical, the diameter of which was only dimi- 
nished when branches were sent off. Beclard believed that they 
have the form of a truncated cone, with the base turned towards 
the heart, some of which, as the carotids, for example, being 
enlarged at the place of division. Others believe with Professor 
Horner,* "that the arterial system in its general configuration 
may be compared to a tree, the trunk of w! ich is attached to 
the heart, and which, by a continued succession of divisions and 
subdivisions reaches to every part of the body. There are no 
means of estimating rigidly the collective area of the branches 
in proportion to that of the trunk; but a little observation on the 
size of the primitive branches, will satisfy one of a great excess 
on the part of the latter, and as the rule is maintained throughout, 
there must finally be an immense disproportion. We have then 
reason to believe, that if all the branches were assembled into a 
single cavity, this cavity would be somewhat like a cone, the 
apex of which would be next the heart. The same rule holds in 
regard to the venous system, it being observed, however, that the 

• A Treatise on General and Special Anatomy, vol. ii. p. 155, by W. E. Horner, 
Prof, of Anat. University Penn., &c. &c. ; fourth edition.— p. 



204 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

latter has two trunks connected with the heart instead of one. 
The general rule is therefore established throughout the vascular 
system, that the collective area of the branches is always greater 
than that of the trunk from which they proceed. By the same 
rule the circulation in the branches must be more languid than 
in the parent trunks, as this circulation is retarded both by addi- 
tional friction, and by having to fill up a larger canal."* 
— Nevertheless, Professor Horner, gives a computation made 
by Mr. Erskine Hazard, from actual measurement of the arte- 
ries, from which it appears, that in many of them at least, the 
area of the large trunks before subdivision is greater than that of 
their divided branches united, and consequently that the blood 
must flow faster through the branches than through the primi- 
tive trunk, as the same quantity of blood must be disposed of in 
the same space of time; and that by this means, friction is re- 
duced, as there is less surface of the vessels exposed to the pass- 
ing of the blood, and thus the force of the heart's action is con- 
tinued much farther through the system. 

— This manifest discrepancy among anatomists of high reputa- 
tion, is explicable by the facts made known from careful measure- 
ment by M. Bizot; viz. that all the different modes of form speci- 
fied, and some others, are met with in the arterial system, and 
that each artery, so to speak, has its peculiar and constant form 
in a healthy state ; the corresponding arteries of the two sides of 
the body, being analogous in form. To establish the truth in 
regard to these points, this writer measured 2,162 arteries, beside 
the measurements of the aorta already given.* All the modes 
of formation of the arteries he reduces to the five following. 

1. A cone, the base of which is directed towards the heart, 
met with 39 times in the 100. 

2. Two truncated cones opposed by their truncated summit, 
met with 28 times in the 100. 

3. A cone with its summit directed towards the heart, met 
with 14 times in the 100. 

4. A perfect cylinder, met with 12 times in the 100. 

* It has been computed that the blood flows 5,233 times slower in the capilla- 
ries than in the aorta. — p. 



THE CAPILLARIES. 205 

5. Two truncated cones opposed by their base, met with 5 
times in the 100. 

— It is seen by this statement that, contrary to the opinion of most 
anatomists, the perfect cylinder is one of the rarest forms. The 
arteria innominata belonged to the second class, or in other words, 
formed a tube narrowed in its middle, in nearly one half of the 
cases in which it was examined. The primitive carotid belonged 
to the same, in more than three-fourths : whilst the same arteries 
but twice in one hundred and thirty-six instances presented the 
form of a cylinder. 

— The brachial, primitive and external iliacs, belonged also to 
the second class in about one-third of the cases examined. In the 
other arteries that form is much more rare. The vessels which 
present the cylindrical form most frequently, are the radial and 
crural arteries. The first form, that of a truncated cone, with the 
base to the heart, is by far most frequent in the arteries of the 
limbs. The popliteal, however, always presents the fifth form, 
that of two truncated cones opposed by their bases, or in other 
words is expanded in its middle at the place where popliteal aneu- 
rism usually occurs. 

Of the Capillaries. 

— The extreme ramifications of the arteries, constitute the ca- 
pillary blood-vessels, which are intermediate to, and form the 
connexion between the arteries and veins, and may be considered 
as the radicles of the latter vessels. The extreme minuteness 
and delicacy of structure of the capillary vessels, are too great 
to admit of any very rigid scrutiny into the structure of their 
walls, but it is considered probable that the internal coat of the 
arteries, is extended through them, so as to be continuous with 
that of the veins. The capillary vessels, were at one time 
considered as having other terminations besides those which 
connected them with the arteries, on one hand, and the veins on 
the other : some were considered, as opening directly into, and 
thus forming the secretory ducts of the different glands; others 
as terminating in like manner, so as to form an imaginary system 
of vessels, called the exhalents, in the skin, and the different 

VOL. II. 18 



206 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

serous and mucous membranes ; and others, according to Lond 
and Lepelletier de la Sarthe, as terminating in the midst of the 
different tissues, so as to allow the molecules of blood to escape 
naked among the organized parts, for the purposes of nutrition. 
It is now, however, pretty generally admitted, that the capillaries 
have no termination but by their anastomoses with each other, 
and their communication with the arteries and veins ; that all 
the fluids which pass from them, for the purposes of nutrition, 
secretion, or exhalation, permeate in some manner their delicate 
coats, by an action, somewhat like the exosmosis of Dutrochet. 
— The direct communication between the arteries and veins, is 
readily shown by the facility with which the veins may be dis- 
tended, by injection of the arteries of the extremities with mer- 
cury. In many of the viscera, also, it is not unusual to fill some 
of the veins, when distending the arteries with size injection. 
— Some anatomists (vide note, p. 198-9) assert that they have 
in the human subject, been able to trace with the microscope, 
the direct continuity of the arteries with the veins. This may be 
done more readily in the inferior animals, especially in the 
reptilia, where the globules of the blood are three or four times 
larger than those of man. 

— In a dissection of a python from South America, and of a boa 
constrictor from the East Indies, made jointly by the late Dr. 
Jno. P. Hopkinson and myself, an account of which was read 
before the American Philosophical Society in 1833, we were 
enabled by the aid of the mercurial pipe and column, to pass 
mercury, in many instances, from a branch of the aorta, into the 
small arteries of the peritoneal investment of the oviducts; and 
by gently pushing the minute columns of mercury forwards 
through these, with the handle of a scalpel, it passed through 
the capillaries into the veins, and the globules of mercury were 
readily forced in a retrograde direction to the vena cava. In 
these cases, when distended with mercury, the capillary vessels 
were very obvious without the aid of a microscope. In the 
transparent parts of animals, as in the mesentery, in the fins 
of some fishes, and in the web of a frog's foot, the microscope 
exhibits very clearly the capillary system of vessels, and the 



THE CAPILLARIES. 



207 




series of blood globules which pass through them from the ar- 
teries to the veins. 

— Fig. 67, is a represent- Fig. 67. 

ation, after Thomson,* of 
the appearance of the ca- 
pillary circulation in the. 
web of a frog's foot. 
The arrows indicate the 
course of the blood, the 
globules of which are seen 
in these vessels arranged 
in a linear series. 
—Marshall Hall, con- 
siders the capillary sys- 
tem/ as a distinct portion, 
reticular in its structure, 
the branches anastomos- 
ing and separating from each other, and yet unlike either the 
arteries or veins, retaining always the same diameter. In the 
lungs he considers this system particularly well developed, and 
that the walls of the ultimate branches of the arteries and veins 
are abruptly terminated, and appear cribriform under the micro- 
scope, when they communicate with or divide into the capillarv 
arteries and veins. 

— These delicate capillary vessels of the lungs are inclosed in the 
mucous membrane, forming the bronchial cells. The mucous 
membrane of these cells being derived from the bronchia, is of 
course continuous throughout the lungs, and may be regarded as 
a delicate membrane filled with a net-work of capillary vessels, 
formed into cells, for the purpose of allowing an extensive super- 
ficies to be comprised in a small space: upon one surface of this 
membrane, the pulmonary vessels maintain a stream of blood, 
divided into currents of the minutest size ; and on the other, air is 
admitted through the bronchia, the oxygen of which acts upon 
the particles of blood in their most divided state. 



* Circulation — Cyclop, of Anat. and Physiology. — p. 



208 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

— The pulmonary or lesser circulation, (which is conducted 
through the pulmonary arteries and veins,) would be perfectly 
isolated from the greater or systemic, (that of the aorta and vena 
cava,) were it not that the bronchial arteries anastomose in the 
lungs with the smaller branches of the pulmonary. 
— The capillary vessels are so abundant, that the spaces left 
between them are believed in man to be less than the dia- 
meter of the vessels themselves. Their diameter has been 
measured by the aid of the microscope, after the vessels had been 
minutely injected, and has been found to vary in different parts of 
the body. The mean of their measurement, according to Muller, 
is between the T7 W n an ^ TsWh part of an inch. No other 
tubes in the body are so minute as the capillary vessels, even 
those of the kidney or testicle. 

Action of the Heart and Arteries. 

— The heswt of an adult man, in the middle period of life, con- 
tracts from seventy to seventy-five times a minute. At each 
pulsation it is calculated that two ounces of blood is ejected. 
The whole amount of blood in the human body has been vari- 
ously estimated, and it is perhaps impossible to arrive at a very 
accurate conclusion upon the subject ; there is certainly a larger 
amount in the body than is usually at one time in active circula- 
tion, a part of it moving slowly, or remaining stagnant for a 
time, in the capillaries of some portions of the body. According 
to Wrisberg, one woman lost by a fatal flooding, 26 lbs. of blood ; 
and in another plethoric woman, who was beheaded, 24 were 
collected. Herbst* has calculated that there is usually about 10 
lbs. of blood in circulation in the human body. It may, therefore, 
be admitted with some certainty, that the circulation of the en- 
tire mass of blood may take place in from one to two minutes. 
— The frequency of the heart's action diminishes gradually from 
the commencement to the end of life, thus :f 

In the embryo, the number of beats in a minute is 150 

Just after birth, - - - - 130 to 140 

* Herbst. De Sang. Quant, etc. Goettingen, 1822. 

{ Mailer's Physiology, (Bennet's translation,) p. 171, vol. i. 



115 to 130 


100 to 115 


90 to 100 


85 to 


90 


80 to 


85 


70 to 


75 


50 to 


65 



ACTION AND SOUNDS OF THE HEART. 209 

During the first year, 

During the second year, 

During the third year, 

About the seventh year, - 

About the fourteenth year, 

In the middle period of life, 

In old age, .... 
— In persons of sanguine temperament the heart beats somewhat 
more frequently than in those of the phlegmatic, and in the 
female sex more frequently than in the male. The number of 
pulsations in the minute vary very much in different animals; it 
is as low as 40 in the horse. 

— The contraction (systole) of the heart, is its only active state ; 
its dilatation (diastole) is effected passively during the moment of 
repose when the fibres are relaxed, by the blood which is poured 
into its cavities from the contiguous veins. Dupuy, a distinguish- 
ed veterinary surgeon of Frankford, found, on introducing his 
hand into the abdomen of a living horse, that the vena cava as- 
cendens becomes turgid during the systole of the heart; and flaccid 
during the diastole, in consequence of the blood rushing from the 
veins into the cavities of the heart. The apex of the heart is 
closely in contact with the ribs, from which it is separated only 
by the pericardium. The body of the heart is also near the inner 
surface of the ribs and sternum; for there is nothing intervening 
beside the pericardium but a thin prolongation of the pulmonary 
tissue. The impulse of the heart, pulsis cordis, is owing to the 
shock communicated to the walls of the thorax in the neighbour- 
hood of the fifth and sixth ribs, and which is believed to take place 
during contraction, by the apex of the heart being lilted upwards 
and forwards. This impulse must not be confounded with the 
arterial pulse or proper sounds of the heart, though it is syn- 
chronous with the first sound. 

— The sounds of the heart are twofold ; the first sound and the 
stronger, is produced by the quick successive contraction of the 
auricles and ventricles. The second sound, as results from the 
recent observations of Dr. Carswell, is produced by the sudden 
closing under the elastic reaction of the arteries, of the semilunar 

18* 



210 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

valves of the aorta and pulmonary artery. The interval between 
these sounds is very slight; it is calculated by Miiller to be 
about the fifth part of a second. 

— The pause which intervenes between the termination of the 
second and the recommencement of the first, is nearly equal to 
the period which elapses between the pulsations of the arteries. 

Of the Pulse. 

— The blood not being able to escape from the arteries into the 
veins through the capillaries, as quickly as it is injected into 
the former by the heart, it necessarily exerts a pressure on the 
elastic coat, which yields both in the direction of its length and 
its diameter. This elastic yielding constitutes the arterial throb 
or pulse. This pulsation is not produced, however, directly, by 
the two ounces of blood injected that moment from the heart ; 
but indirectly, in consequence of these two ounces injected into 
the base of the column of blood, with which the aortic system is 
filled and the transmission of the shock through the whole arte- 
rial system driving out at the other extremity a corresponding 
quantity into the veins. The impulse of the heart is transmitted 
by the oscillation of the particles, along the vessels, (precisely as 
takes place when a shock is communicated to a column of water 
in a hose,) and this constitutes the pulse. The elastic force of the 
arteries when distended is very familiar to those who are in the 
habit of injecting them for anatomical study. By partially filling 
the vessels with a thin fluid and then throwing in more fluid by 
jerks, we may readily produce a sort of artificial pulse. — 

Of the Veins. 

These tubes, which return to the heart the blood carried from 
it by the arteries, are more numerous than the arteries, and often 
are larger in diameter. 

They generally accompany the arteries, and very often two 
veins are found with one artery. These are called the vence comties. 

In addition to these last mentioned veins, which may also be 
called deep-seated, there are many subcutaneous veins which ap- 
pear on almost every part of the surface of the body. 



GENERAL ANATOMY OF THE VEINS. gH 

The capacity of all the veins is therefore much greater than 
that of all the arteries. 

Those subcutaneous veins which are of considerable size, 
communicate very freely with each other, and also with the 
deep-seated veins. 

The trunks of the veins, in those places where no branches go 
off, are generally cylindrical. There are, however, some excep- 
tions, in which these vessels are irregularly dilated, as sometimes 
happens in the case of the internal jugular vein. It is, however, 
not easy to determine from the appearance of veins injected 
after death, respecting their situation during life, as their coats 
are very yielding; and it is very probable that they are, there- 
fore, preternaturally dilated by the injection. 

Feins, directly or indirectly, originate from the termination of 
arteries : but they do not pulsate as the arteries do, because the 
impulse given to the blood by the heart is very much diminished 
in consequence of the great diminution of the size of the vessels 
through which the blood has passed. 

In some cases, however, when blood flows from an opened 
vein, the extent of its projection is alternately increased and 
diminished, in quick succession, as if it were influenced by the 
pulsation of the heart. 

The Coats of Veins differ considerably from those of Arte- 
ries, — for they are thinner, and so much less firm, that veins, 
unlike arteries, collapse when they are empty. 

They consist of a dense elastic substance, the fibres of which 
are much less distinct than those of arteries, but some of them 
are to be seen in a longitudinal direction. These fibres can be 
made to contract by local irritation ; for if a vein be laid bare in 
a living animal, and then punctured, it will often contract so as 
to diminish its diameter very considerably, although no blood 
shall have escaped from the punctures. 

Next to the elastic substance is the internal coat, which is 
smooth and polished. It is separated from the substance exterior 
to it with difficulty, although it may be taken from it very easily 
in the vena cava. 

This internal coat is more ostensible than the internal coat of 
arteries, and is not, like the latter, disposed to ossification. It is 



212 GENERAL ANATOMY OF THE SANGUIFEROUS SYSTEM. 

frequently so arranged as to form valves, which are plaits or folds, 
of a semilunar form, that project from the surfaces into the cavi- 
ties of these vessels.* 

Two of these valves are generally placed opposite to each 
other; and, when raised up, they form a septum in the cylindrical 
cavity of the vessel. The septum, thus composed, is concave 
towards the heart, (see Fig. 66, p. 191.) 

The valves have a great effect in preventing the contents of 
the veins from moving in a retrograde course : they therefore 
necessarily modify the effects of lateral pressure, in such a man- 
ner, that it propels the blood forward, or to the heart. 

These valves are generally found in the veins of the muscular 
parts of the body, especially in those of the extremities. They 
are not found in those veins which are in the cavities of the 
body, nor in the internal jugulars. They are placed at unequal 
distances from each other. 

The coats of the veins are somewhat transparent ; and there- 
fore those veins which are subcutaneous have a bluish aspect, 
which is derived from the colour of the blood they contain. 

The colour of the blood in the veins is different from that in 
the arteries, being of a darker red. 

The situation and arrangement of the large trunks of veins is 
much alike in different subjects ; but the branches, especially 
those which are subcutaneous, are very variable in their situa- 
tions. 

Of the Blood. 

The blood of a healthy person indicates a tendency to coagu- 
late very soon after it is discharged from the vessels which na- 
turally contain it, although it is perfectly fluid in those vessels. 

If it remain at rest, after it is drawn from the vessels, it soon 
coagulates into a solid mass, of a soft texture. From this solid 
mass a fluid is soon observed to issue, which appears in very 

* The valves of the veins were first described by Charles Etienne of Paris, in 
1546. In 1547, Amatus, a Portuguese, saw at Ferrara, those at the mouth of the 
vena azygos. Sylvius, of Paris, announced them about the same time in the ju- 
gular, brachial and crural veins. Fabricus ab Aquapendente claims the discovery 
for himself in 1574. Lassus. — h. 



THE BLOOD. 2J3 

small drops on almost every part of the surface. These drops 
quickly increase and run together, and in a short time the fluid' 
surrounds the solid mass, and exceeds it in quantity. 

The solid part which thus appears upon the spontaneous se- 
paration of the blood, is denominated Crassamentum or Cruror; 
the fluid part is called Serum. 

The substance which contains the red colour of the blood, 
remains with the Crassamentum. The Serum, when it separates 
without agitation, is free from the red colour. 

The colouring matter may be separated completely from the 
Crassamentum by washing it with water. 

The blood, therefore, consists of three parts, namely; the 
Serum ; the substance which coagulates spontaneously (fibrine) ; 
and the Colouring Matter. 

— If the blood be examined with the microscope in the vessels 
of a transparent part, or immediately after it has flowed from 
the body, it is seen to consist of small red particles or globules, 
and a clear colourless fluid. This fluid is the lympha or liquor 
sanguinis, and must not be confounded with the serum, which 
separates from the crassamentum during coagulation. It can be 
obtained free from the red globules, before coagulation takes 
place, by filtering the blood of a frog or some other animal, in 
which the red globules are so large as not to pass through the 
pores of the filtering paper. The liquor sanguinis, consists of 
the serum of the blood that holds the fibrine, which is also co- 
lourless, in a state of solution. When the fibrine coagulates, it 
encloses within it the red particles, and the watery part of the 
blood (serum) is left, which holds the albumen in solution. — 

The Serum 

Has a considerable degree of consistence, although it is much 
thinner than blood. In its perfectly natural state, it is almost 
transparent, and appears to be very lightly tinged with a greenish 
yellow colour ; but it is very often impregnated with a portion 
of bile, which is probably carried to the blood-vessels by the ab- 
sorbents. It contains a large quantity of albumen, or matter like 
the white of an egg. If heated to 140° of Fahrenheit, it be- 



214 THE BLOOD. 

comes opaque; and when the heat is increased to 156° or 100,° it 
is firmly coagulated. It is also coagulated by alcohol, by mineral 
acids, and by rennet.* It is proved by chemists, that it contains 
a small quantity of pure soda. It therefore changes several of the 
blue colours of vegetables to green. It is also found to contain 
a similar quantity of the muriate and the phosphate of soda and 
the phosphate of lime. These saline substances were discovered 
by diluting serum with water, and exposing the mixture to heat, 
by which the albumen was coagulated into fiocculi ; these floc- 
culi were separated by filtration ; the liquor was then diminished 
by evaporation, and the salts obtained from it by crystallization. 

Serum likewise contains a portion of sulphur combined with 
ammonia. 

When it is exposed to a coagulating heat, a small portion of 
it remains fluid. 

This fluid portion has been supposed to contain a considerable 
quantity of gelatine ; but it is contended by Mr. Brande,f that 
Gelatine does not exist in the serum of the blood, and that this 
portion consists of albumen combined with a proportion of 
alkali. 

It is also asserted by Dr. Bostock,J one of the latest writers on 
the subject, that the serosity of blood, (the term applied to the 
last mentioned fluid,) contains no gelatine; but that, with a mi- 
nute quantity of albumen, it consists of a large portion of an 
animal matter, which is different either from gelatine or albumen, 
being unlike either of them, in its chemical qualities. 

The Crassamentum 

Is rendered very different in its appearance, by the different 
circumstances in which it may coagulate. 

When the blood remains at rest immediately after it is drawn, 

* See Hewson, vol. i. 139.— I suspect that some particular management is ne- 
cessary in the use of rennet. 

t In his Researches on the Blood, communicated to the Royal Society of Lon- 
don, in 1812, and republished in the Eclectic Repertory, for April, 1813. 

t See his Observations on the Serum of the Blood, in the Medico-Chirurgical 
Transactions, vol. ii. republished in the Eclectic Repertory, for October, 1812. 



THE BLOOD. 215 

the crassamentum which forms in it is a concrete substance, 
without the smallest appearance of fibre in its composition. If 
the blood is stirred with a rough stick, while it is flowing from 
an animal, a large portion of it will concrete upon the stick in a 
fibrous form, so as to resemble a mass of entangled thread, some 
of the red colouring matter still adhering to it. 

The crassamentum, in either of these forms, may be washed 
perfectly white ; the red colouring matter passing completely 
away with the water. In this state it appears* to have all the 
chemical properties of the fibrous matter of muscular flesh. It 
also resembles the gluten of vegetables, being soft and elastic. 
The name fibrine is now generally applied to it. 

If fibrixe is washed and dried, its weight is very small indeed 
when compared with that of the blood from which it has been 
obtained. It is, therefore, probable that a considerable propor- 
tion of the bulk of the crassamentum, as it forms spontaneously, 
depends upon the serum which exists in it, and can be washed 
away. 

The spontaneous coagulation of the blood, which appears to 
depend principally upon the Fibrine, may be prevented by the 
addition of several foreign substances to the blood, when it is 
drawn. It is subject to great variations that depend upon the 
state of the body at the time of bleeding ; and in some condi- 
tions, it does not take place at all.f 

In a majority of dead subjects the blood is found more or less 
coagulated in the veins; but in some subjects it is found without 
coagulation. It is asserted that it does not coagulate in subjects 
who have died suddenly, in consequence of anger, lightning, or 
a blow on the stomach. 

The Colouring Matter. 
When the blood-vessels in the transparent parts of certain liv- 

* By the experiments of Mr. Charles Hatchett, published in the London Philo- 
sophical Transactions for 1800. 

t See an Inquiry into the Properties of the Blood, by the late William Hewson : 
and Experiments by his son, T. T. Hewson, in the Eclectic Repertory, Jan. 1811. 
See, also, a Treatise on the Blood, &c. by the late J. Hunter. 



216 THE BLOOD. 

ing animals are examined with magnifying glasses, it appears 
that the red colour of the blood is owing to bodies of a globular 
form, which are diffused through a transparent fluid. The ap- 
pearance of these bodies has been examined, with, great atten- 
tion, by many physiologists, since the publication of Leuenhoeck, 
in the London Philosophical Transactions.* 

Several of these gentlemen have described the appearance of 
the blood very differently ; but Haller, Spallanzani and J. Hunter 
agree that the figure of the red particles is globular.f Hunter 
observes farther, that the red globules do not run into each other 
as two globules of oil would do when divided by water; and he 
believes that they cannot unite. At the same time they seem not 
to have the properties of a solid: for when circulating in the 
vessels, they assume elliptical forms, adapting themselves to the 
size of the vessels. They also excite no sensation of solidity 
when touched. 

They appear to be more heavy than the other parts of the 
crassamentum : for in healthy blood the lower part of the mass 
contains more of the colouring matter than the upper part ; and 
in the blood of persons who labour under acute local inflamma- 
tion, they often subside completely from the upper part; and thus 

* Among the most distinguished of these observers were Father De la Torre, Hal- 
ler, Hewson, Fontana, Spallanzani, J. Hunter, Cavallo. 

Some short accounts of Leuenhoeck's original observations on the Blood are to 
be found in the Philosophical Transactions of London, for 1664, in the fasciculi 
which are numbered 102 and 106. A more full description is contained in Boer- 
haave's Academical Lectures on the Theory of Physic. See the section on the 
nature of the blood. 

The glasses of Father De la Torre were transmitted from Naples to the Royal 
Society of London in 1765. They were accompanied by a letter from Sir F. H. 
E. Stiles, to which are subjoined some observations by the Rev. Father himself. 
The letter and the observations are published in the 55th volume of the Transac- 
tions of that society. 

In the year 1798, Tiberius Cavallo published an Essay on the Medicinal Proper- 
ties of Factitious Air, with an Appendix on the Nature of the Blood, in which is 
contained a farther account of the glasses of De la Torre. 

t I believe that this is also the opinion of Fontana.— In J. Hunter's work on the 
blood there are some interesting observations on microscopical deceptions. See 
the note commencing in page 39, Bradford's edition. 



THE BLOOD. 217 

occasion what is called by Mr. Hewson the inflammatory crust, 
or size. 

It has been observed by Mr. Hewson, and also by Mr. Hun- 
ter, that the globules do not retain their form in every fluid. 
They are said to be dissolved very quickly in water, and then they 
form a fine clear red. Several of the neutral salts, when dis- 
solved in water, prevent the solution of the globules. Mr. Hun- 
ter informs us, that the vitriolic acid, when greatly diluted, does 
not dissolve them, &c. The muriatic acid, when three times as 
strong as vinegar, destroys their colour without dissolving them, 
although when more diluted, it dissolves them. 

— Hewson described the red globules as being flattened, and 
was the first to discover distinctly, the dark spot in the centre, 
formed by the central nucleus. Modern improvements in the man- 
ner of using the microscope, have confirmed his views, and 
shown that the globules of blood in different animals, are always 
flattened, and that they vary in their outline, from the elliptical 
to the circular form. 

— In the mammalia, including man, they are circular Fig. 68.* 
disks; that is, globules flattened upon the sides. In Fig. a 
birds, reptiles, and fishes, they are elliptical ; the long 
diameter being twice that of the transverse. In the 
globules of human blood, their thickness is about one- 
fourth or one-fifth of their transverse diameter. The size 
of the red globules varies very much in different ani- 
mals, and to some extent among themselves, even in 
the same animals. But in man and most other ani- 
mals, the variation in size, never amounts to a dou- 
bling of the diameter. The size of the red globules in the 
amphibia, is greater than in any other class of animals. The 
long diameter of the red globules in the frog, is four times that 
of the circular diameter of those of man. The diameter of the 
red particles in man have been variously stated, from the 77r Wth 
to the TtfVoth part of an English inch. 

* Fig. 68. a, Globule of human blood, b, Of sheep's blood, c, Of the blood 
of a sparrow. These globules are magnified a thousand times in diameter.— p. 
VOL. ii. 19 





218 THE BLOOD. 

— In the centre of all the red particles there is a dark spot, which 
is elliptical in shape, in all animals in which the general shape of 
the particle is elliptical ; and round in those in which the parti- 
cles are circular and flattened. These spots or nuclei, when 
viewed with the light in a particular situation, reflect it, and pre- 
sent the appearance of holes, which at one time induced the be- 
lief, that the particles were annular in shape. 
Most of the recent microscopical observers have 
satisfied themselves of the correctness of Hew- 
son's opinion, that the dark spot in the cen- 
tre, is owing to the presence of a solid nucleus 
in each particle. The outer vesicle, which en- 
closes the nucleus, is seen torn, (see Fig. 70,) 
showing the nucleus in one of the red particles of 
the frog. 

— These vesicles contain the colouring matter of the blood, and 
under particular treatment, are rendered soluble, and the naked 
nuclei are precipitated in the form of minute granules. Under 
any treatment, the latter are found to be insoluble. 

Chyle Globules. 

— In the blood, Hewson also observed some minute globules, 
which he considered those of the chyle. They have since been 
observed by Miiller and others. They are abundant in the chyle, 
in the lymph, and are probably, as Hewson suggested, identical 
with the nuclei of the red particles. According to Prevost and 
Dumas, their diameter is precisely the same as that of the primi- 
tive muscular fibre, the yrWth part of an inch. — 

The colour of the blood has, for a long time, been supposed 
to depend upon iron. About the middle of the last century, Vi- 
centius Menghini published in the Transactions of the Academy 
of Sciences of Bologna, an account of experiments which con- 
tributed to establish this sentiment. In this account he stated 
that, after washing the colouring matter from the crassamentum, 

* Fig. 69. d, Globule of frog's blood, magnified seven 1 hundred times, and seen 
in profile, c, Front view of the same, in which the envelope or colouring matter is 
torn, so as to exhibit the central nucleus. — p. 



THE BLOOD. 



219 



he had separated it from the water by boiling ; in which case it 
either rose to the surface of the water, or subsided, and left the 
water clear. After drying with a gentle heat, some of the colour- 
ing matter thus separated, and then repeatedly washing it, he 
found that it contained a considerable quantity of iron, which 
was attracted by the magnet. 

After exposing a large quantity of the colouring matter to an 
intense heat, he found in it a small piece of iron, of a spherical 
form, but hollow; and a powder which was attracted by the 
magnet, but appeared more like rust of iron than iron filings. 

He believes the seat of this iron to be in the colouring matter 
of the blood, as neither the serum nor fibrine appeared to con- 
tain it. According to his calculation, the blood of a healthy 
man contains more than two ounces of iron. 

This doctrine of Menghini has been very generally admitted : 
and by several chemists of the first character, namely, Bucquet, 
Fourcroy, Vauquelin, &c. 



220 THE AORTA. 



CHAPTER VIII. 

A PARTICULAR ACCOUNT OF THE DISTRIBUTION OF THE ARTERIES. 

Of the Aorta,* or the Great Trunk of the Arterial System. 

When the heart is in its natural position, the right ventricle 
is nearly anterior to the left, and therefore, the Aorta, where it 
originates from the left ventricle, is behind the pulmonary artery, 
and covered by it. Its first direction is so oblique towards the 
right side of the body, that it crosses the pulmonary artery be- 
hind, and appears on the right side of it. It has scarcely assumed 
this position before its course alters, for it then proceeds obliquely 
backwards and to the left ; so as to form a large curve or arch, 
which extends to the left of the spine. 

The position of this curve or arch is so oblique, with respect 
to the body, that the cord or diameter of it, if it were extended 
anteriorly and posteriorly, would strike the cartilage of the second 
or third right rib about the middle of its length, and the left rib 
near the head. In consequence of this position of the curve, the 
Aorta crosses over the right branch of the pulmonary artery, and 
the left branch of the windpipe : and assumes a situation, in front, 
and to the left of the third dorsal vertebra : from this situation it 
proceeds downwards : in front, but rather on the left side of the 
spine, and in contact with that column. 

The Aorta, as well as the Pulmonary Artery, for a small dis- 
tance from the heart, is invested by the pericardium ; and, when 
that sac is opened, appears to be contained in it. 

After crossing the right branch of the Pulmonary Artery, a 

* This name was given by Aristotle. — h. 



AORTA. 221 

ligament is inserted into it, which proceeds from the main trunk 
of the pulmonary artery at its division : this ligament was the 
Canalis Arteriosus in the foetus. 

As the Aorta proceeds down the spine, it is situated between 
the two lamina of the mediastinum, and in contact with the left 
lamen, through which it may be seen. It descends between the 
crura of the diaphragm, in a vacuity which is sufficiently large 
to admit of its passage without pressure from the surrounding 
parts, and is still in contact with the anterior surface of the spine, 
but rather to the left of the middle of it. It continues this course 
along the spine until it arrives at the cartilaginous substance be- 
tween the fourth and fifth lumbar vertebras, when it divides into 
two great branches of equal size, which form an acute angle 
with each other. These are denominated the Common or Primi- 
tive Iliac arteries. 

From the Aorta in this course are sent off the arteries which 
are distributed to all the parts of the body for their nourishment 
and animation. 

From the curve proceed the great branches which supply the 
heart, the head, the upper extremities, and part of the thorax. 
Between the curve and the great primitive iliac arteries, the 
Aorta sends off those branches which supply the viscera contain- 
ed in the cavities of the thorax and abdomen,* and part of the 
trunk of the body. The great Iliac branches of the Aorta 
are divided into smaller arteries, which supply the whole of the 
lower extremities and some of the viscera of the pelvis. 

Of the Branches which go off from the Arch of the Aorta. 

The proper arteries of the heart, denominated Coronary Ar- 
teries, proceed from the Aorta so near to the heart that their ori- 
fices are covered by the semilunar valves, when those valves are 
pressed against the sides of the artery. These arteries have 
been described in the account of the heart, (see page 468, vol. i.) 

The arteries of the head and of the upper extremities proceed 
from the upper part of the curve in the following manner. 

* It ought to be observed here, that the viscera, in the lower part of the pelvis, 
receive some branches from the internal iliac arteries. 

19* 



222 ARTERIA INNOMINATA.— CAROTID ARTERIES. 

A large trunk, called Arteria Innominata, goes off first. This 
is more than sixteen lines in length, when it divides into two 
branches, one of which supplies the right side of the head, and 
is denominated the Right Carotid : the other proceeds to the 
right arm, and from its course under the clavicle, is called, at 
first, the Right Subclavian. Almost in contact with the first 
trunk, another artery goes off, which proceeds to the left side of 
the head, and is called the Left Carotid. Very near to this, 
arises the third artery, which proceeds to the left arm, and is de- 
nominated the Left Subclavian. From these great branches 
originate the blood-vessels, which are spent upon the head and 
neck and the upper extremities. 

As these arteries arise from the curve of the Aorta, they are 
situated obliquely with respect to each other. The Arteria In- 
nominata is not only to the right, but it is also anterior to the two 
others : and the Left Subclavian is posterior, as well as to the 
left of the Left Carotid and the Arteria Innominata. 

The Carotid Arteries. 

The two carotid arteries above mentioned have been denomi- 
nated Common Carotids, to distinguish them from their first rami- 
fications, which are called Internal and External Carotids. 

The Common Carotids 

Proceed towards the head on each side of the trachea : at 
first they diverge, but they soon become nearly parallel to each 
other, and continue so until they have ascended as high as the 
upper edge of the thyroid cartilage, when they divide into the 
Internal and External Carotids. 

These arteries are at first very near each other, and rather in 
front of the trachea ; they gradually diverge and pass backwards 
and outwards on the sides of it, and of the oesophagus, until 
they have arrived at the larynx. In the lower part of the neck 
they are covered by the sterno-mastoidei, the sterno-hyoidei, and 
thyroidei, as well as by the platysma myoidei muscles. Above, 
their situation is more superficial ; and they are immediately 
under the platysma myoides. 



EXTERNAL CAROTID. 223 

On the inside, they are very near the trachea and larynx, and 
the oesophagus ; on the outside, and rather anterior to them, are 
the internal jugular veins ; and behind, on each side, are two im- 
portant nerves called the intercostal and the par vagum. These 
blood-vessels and nerves are surrounded by absorbent vessels. 

The Common Carotid Arteries send off no branches from their 
origin to their bifurcation ; and they appear to preserve the 
same diameter throughout their whole extent. In some few in- 
stances the right carotid has been found larger than the left. 
The external and internal branches into which they divide, are 
nearly equal in the aJult; but it is supposed that the internal is 
the largest during infancy. The relative position of these 
branches is also different at the commencement from what it is 
afterwards. The Internal Carotid forms a curve which projects 
outwardly, so as to be exterior to the External Carotid, while 
this last proceeds upwards, and rather backwards. 

The External Carotid Artery 

May be considered as extending from its commencement, 
which is on a line with the superior margin of the thyroid car- 
tilage, to the neck of the condyle of the lower jaw, or near it. 

At first it is superficial ; but as it proceeds upwards it becomes 
deep-seated: and passing under the digastric and stylo-hyoidei 
muscles, and the ninth pair of nerves, is covered by the Parotid 
Gland. After this, it again becomes superficial ; for the tem- 
poral artery, which may be regarded as the continuation of the 
external carotid, passes over the zygomatic process of the tem- 
poral bone. 

As the External Carotid supplies with blood the upper part of 
the neck and throat, the exterior of the head and face, and the 
inside of the mouth and nose ; its branches must necessarily be 
numerous, and must pass in very various directions. 

Thus, soon after its commencement, it sends off, in an anterior 
direction, three large branches ; viz. to the upper part of the neck, 
to the parts within the lower jaw, and to the cheeks and lips. 
These are denominated, the Superior Thyroid, the Sublingual, 
and the Facial It then sends off to the back of the head one 



224 SUPERIOR THYROID.— LINGUAL. 

which is called the Occipital; and, as it proceeds upwards near 
the condyle of the lower jaw, another which passes internally, 
behind the jaw, to the deep-seated parts in that direction. After 
this, it forms the temporal artery, which supplies the forehead 
and central parts of the cranium. Besides these larger branches, 
the external carotid sends off two which are smaller; one from 
near the origin of the sublingual artery, which is spent principal- 
ly upon the pharynx and fauces, and is called the Inferior Pha- 
ryngeal : and another, while it is involved with the parotid 
gland, which goes to the ear; and is therefore called Posterior 
Auris. 

These arteries are distributed in the following manner: 

1. The Superior Thyroid Branch 

Comes off very near the root of the external carotid, and 
sometimes from the common trunk; it runs obliquely downwards 
and forwards, in a meandering course, to the thyroid gland, 
where it is spent. During this course it sends off one- branch to 
the parts contiguous to the os hyoides ; another to the neigh- 
bourhood of the larynx : and a third branch which may be 
termed laryngeal, that passes with a small nerve derived from 
the laryngeal branch of the par vagum, either between the os 
hyoides and thyroid cartilage, or the thyroid and cricoid car- 
tilages, to the interior muscles of the larynx ; and finally returns 
again to terminate externally. 

While in the thyroid gland this artery anastomoses with the 
inferior thyroid, and also with its fellow on the opposite side. 

2. The Lingual, or Sublingual Branch, 

Goes off above the last mentioned artery, and very near it ; 
but in a very different direction, for it runs upwards and forwards, 
to the tongue. In this course it crosses obliquely the os hyoides, 
and is commonly within the hyoglossus muscle. It gives off 
branches to the middle constrictors of the pharynx, and to the 
muscles contiguous to the tongue. It also sends off a branch 
which penetrates to the back of the tongue, which is called, from 
its situation, Dorsalis Lingua. At the anterior margin of the 



FACIAL ARTERY. 225 

liyoglossus muscle it divides into two branches, one of which 
passes to the sublingual gland and the adjacent parts, and is 
thence called Sublingual; while the other branch, the Ranina, 
passes by the side of the genio-glossus muscle to the apex of the 
tongue. 

3. The Facial or External Maxillary 

Runs obliquely upwards and forwards under the ninth pair of 
nerves, the stylo-hyoideus muscle and the tendon of the digastric, 
across the lower jaw and cheek, towards the inner corner of the 
eye, in a serpentine course. Before it crosses the jaw it sends off 
several branches, viz. to the pharynx, the tonsils, the inferior max- 
illary gland and the parts contiguous to it. It also sends a branch 
towards the chin, which passes between the mylo-hyoideus, the 
anterior belly of the digastric, and the margin of the lower jaw : 
and some of its branches continue to the muscles of the under 
lip. This branch is called the Submental. 

This artery then passes round the basis or inferior edge of the 
lower jaw, very near the anterior margin of the masseter muscle, 
and is so superficial that its pulsations can be readily perceived. 
After this turn, its course is obliquely upwards and forwards. 
Near the basis of the jaw it sends off a branch to the masseter, 
which anastomoses with small branches from the temporal; and. 
another which passes superficially to the under lip and contiguous 
parts of the cheeks. This last is called the Inferior Labial. 

After the artery has passed as high as the teeth in the lower 
jaw, it divides into two branches ; which go, one to the under, 
and the other to the upper lip ; that to the upper lip is largest. 
These branches are called Coronary. 

The Coronary Artery of the lower lip passes under the muscles 
called Depressor Anguli Oris, and Orbicularis Oris, into the sub- 
stance of the lip, and anastomoses with its fellow of the opposite 
side. 

The Coronary Artery of the upper lip passes under the zygo- 
matics major and the orbicularis, and very near the margin of 
the upper lip internally. It also anastomoses freely with its 
fellow on the opposite side. These anastomoses are frequently 



226 INFERIOR PHARYNGEAL.— OCCIPITAL. 

so considerable that the arteries on one side can be well filled by 
injecting those of the other. The coronary branches, as well as 
the main trunk of the facial artery, observe a serpentine or tor- 
tuous course ; in consequence of which they admit of the motions 
of the cheeks and lips, which they would greatly impede, if they 
were straight. 

From the upper coronary artery a branch continues in the 
direction of the main trunk of the facial artery, by the side of the 
nose, which extends upwards, sending off small branches in its 
course, and finally terminates about the internal angle of the eye 
and the forehead. 

4. The Inferior Pharyngeal 

Is a very small artery; it rises posteriorly from the external 
carotid, opposite to the origin of the sublingual, and passes up- 
wards to the basis of the cranium. In this course it sends several 
branches to the pharynx, and to the deep-seated parts imme- 
diately contiguous. 

It also sends branches to the first ganglion of the intercostal 
nerve, to the par vagum, and to the lymphatic glands of the 
neck ; and, finally, it enters the cavity of the cranium by the 
posterior foramen lacerum. 

In some cases it also sends a small branch through the anterior 
foramen lacerum. 

5. The Occipital Artery 

Arises from the posterior side of the external carotid, nearly 
opposite to the facial, but sometimes higher up ; it ascends ob- 
liquely, and passes to the back part of the cranium, between the 
transverse process of the atlas and the mastoid process of the 
temporal bone. 

In this course it passes over the internal jugular vein and the 
eighth pair of nerves, and under the posterior part of the digastric 
muscle: it lies very near to the base of the mastoid process, and 
under the muscles which are inserted into it. After emerging 
from these muscles, it runs superficially upon the occiput, dividing 
into branches which extend to those of the temporal artery. 



POSTERIOR AURIS OR STYLOMASTOID ARTERY. £27 

The Occipital Artery sends off branches to the muscles which 
are contiguous to it, and to the glands of the neck. 

It also gives off the following branches ; one called the Me- 
ningeal, which passes through the posterior foramen lacerum to 
the under and back part of the dura mater: one to the exterior 
parts of the ear: another which passes downwards, and is spent 
upon the complexus, trachelo-mastoideus, and other muscles of 
the neck : and several smaller arteries. 

The artery next to be described, is sometimes sent off by the 
occipital artery. 

6. The Posterior Auricular, or Stylo- Mastoid Artery. 

When it arises from the external carotid, comes off posteriorly 
from the artery, where it is involved with the parotid gland, and 
passes backwards between the meatus auditorius externus and 
the mastoid process. It then ascends, in a curved direction, and 
terminates behind the ear. 

In this course it sends off small branches to the parotid gland, 
and to the digastric and sterno-mastoid muscles. Sometimes a 
distinct branch, which is particularly visible in children, passes 
through an aperture in the meatus auditorius externus, and is 
spent on its internal surface. 

It also sends off a branch which enters into the Stylo-Mastoid 
Foramen, and supplies small vessels to the membrana tvmpani 
and the lining membrane of the cavity of the tympanum ; to the 
mastoid cells; to the muscle of the stapes, and to the external 
semicircular canal. One of these vessels anastomoses in the 
upper and posterior part of the cavity of the tympanum, with a 
small twig derived from the artery of the dura mater. When it 
has arrived behind the ear, the Posterior Auricular Artery termi- 
nates upon the external ear and the pnrts contiguous to it. 

Distribution of the Branches of the External Carotid Artery, after 
Sir Charles Bell. (See Plate facing page 228.) 

a. The Common Carotid Artery, 

b. The Internal Carotid Artery, or Artery of the Cerebrum. 

c. The External Carotid Artery. 



228 TEMPORAL ARTERV. 

i>. The Lower Thyroid Artery, being a branch of the Subclavian Artery. 
e. The Upper Thyroid Artery, being the first branch of the Carotid. 

Branches of the External Carotid Artery. 

1. The Lingual Artery. 

2. The Facial Artery or Labial Artery. 

3. The Submental Artery. 

4. The Upper and Lower Coronary Arteries. 

5. The Inosculations of the extreme Branches of the Facial Artery, with 
the Ophthalmic Artery. 

6. The Occipital Artery. 

7. The place where it frequently sends down inosculations to the vertebral 
artery. 

8. The Lesser Posterior Artery of the Ear. 

9. A Branch sometimes called Posterior Temporal Artery. 

10. Posterior Artery of the Ear, or Stylo-mastoid. 

11. The continued Branch of the External Carotid, sometimes called the 
Temporal Artery ; it divides into the submaxillary and proper temporal 
artery. 

12. The Internal Maxillary Artery. See the distribution of this artery in 
the next Plate, Fig. I. 14, and Fig. II. 

13. The Transverse Artery of the Face. 

14. The Temporal Artery, dividing into anterior and posterior temporal ar- 
teries. There are other branches less superficial. The deep Temporal 
is a branch of the Internal Maxillary. 

7. The Temporal Artery 

Is considered as the continuation of the external carotid, be- 
cause it preserves the direction of the main trunk; although the 
internal maxillary is larger. 

After parting with the internal maxillary it projects outwards ; 
and passing between the meatus auditorius externus and the 
condyle of the lower jaw, continues upwards, behind the root of 
the zygomatic process of the temporal bone, to the aponeurosis 
of the temporal muscle: on the outside of which, immediately 
under the integuments, it divides into two large branches deno- 
minated anterior and posterior. 

Before this division the temporal artery sends off several 
branches of very different sizes. 

One, which is considerable in size, and called the Transverse 



I'll/, III 









m ■■. 
















{ȣn o,: 



INTERNAL MAXILLARY ARTERY. 



229 



Facial Branch, advances forwards across the neck of the con- 
dyle of the lower jaw, and giving small branches to the masseter, 
runs parallel to the parotid duct, and below it. This branch is 
spent upon the muscles of the face, and anastomoses with the 
other vessels of that part. 

The temporal gives off small branches to the parotid gland 
and to the articulation of the jaw. From the last mentioned 
branch small twigs pass to the ear, one of which enters the 
cavity of the tympanum by the glenoid fissure. 

While this artery is on a line with the zygoma, it sends off a 
branch called the middle temporal artery, which penetrates the 
aponeurosis of the temporal muscle, and ramifies under it upon 
the muscle in an anterior direction. 

The two great branches of the temporal artery are distributed 
in the following manner. The Anterior passes up in a serpen- 
tine direction on the anterior part of the temple, and supplies the 
front side of the head and the upper part of the forehead. 

The Posterior extends upwards and backwards, and supplies 
the scalp on the lateral and middle part of the cranium, and also 
the bone. 

Ramifications from each of these branches anastomose on the 
upper part of the cranium with those of its fellow of the opposite 
side. The anterior branch also anastomoses on the forehead 
with the facial and ophthalmic arteries; and the posterior branch 
with the occipital artery on the back part of the head. 

8. The Internal Maxillary Artery* 

Arises from the external carotid under the parotid gland, at a 
little distance below the neck of the condyloid process of the 
lower jaw, and extends to the bottom of the zygomatic fossa 

* The general situation of this artery, and the distribution of several of its most 
important branches, cannot be understood without a knowledge of the bones 
through which they pass. The student of surgery will therefore derive benefit 
from a reexamination of these bones, and of the zygomatic fossa, &c. when he 
studies this artery. (See vol. i. page 114.) He ought to be well acquainted with 
this subject, if he should undertake the management of necrosis of the jaw bones; 
or of those fungous tumours, which sometimes originate in the antrum maxillare; 
as well as of several other complaints. 

VOL. II. 20 



230 INTERNAL MAXILLARY ARTERY. 

varying, its direction in its course. It is rather larger than the 
temporal. 

a. It first sends off one or two small branches to the ear, and 
a twig which penetrates into the cavity of the tympanum by the 
glenoid fissure. 

b. It also sends off a small artery called the Lesser Meningeal, 
which passes upwards, and after giving branches to the external 
pterygoid and the muscles of the palate, passes through the 
foramen ovale, and is spent upon the dura mater about the sella 
turcica. 

c. It then sends off one of its largest branches, the Great or 
middle Artery of the Dura Mater, which passes in a straight di- 
rection to the foramen spinale, by which it enters into the cavity 
of the cranium. 

This artery ramifies largely on the dura mater, and makes 
those arborescent impressions which are so visible in the parietal 
bone. It generally divides into two great branches : the anterior 
of which is the largest, passes over the anterior and inferior 
angle of the parietal bone : the posterior branch soon divides 
into many ramifications, which are extended laterally and pos- 
teriorly. 

It furnishes the twig which passes to the ear by the hiatus of 
Fallopius, and anastomoses with the small branches of the stylo- 
mastoid artery. 

It also supplies some other small vessels which pass to the 
cavity of the tympanum by small foramina near the junction of 
the squamous and petrous portions of the temporal bone. 

d. The next branch sent off by the internal maxillary leaves 
it about an inch from its origin, and is called the Inferior Max- 
illary. It passes between the internal pterygoid muscle and the 
bone, and after giving small branches to the contiguous muscles, 
enters the canal in the lower jaw, in company with the nerve. 
This canal has a very free communication with the cellular 
structure of the jaw, and the artery in its progress along it sends 
branches to the respective teeth and the bone. At the anterior 
maxillary foramen this artery sends off a considerable branch 
which passes out and anastomoses with the vessels on the chin, 



INTERNAL MAXILLARY ARTERY. 231 

while another branch passes forward and supplies the canine 
and incisor teeth and the bone contiguous to them. 

Sometimes the inferior maxillary artery divides into two 
branches before it has arrived at this foramen. In this case, 
one of the arteries passes out of the foramen, while the other 
continues to the symphysis. 

b. Two branches pass off to the temporal muscle, which ori- 
ginate at a small distance from each other ; one of them passes 
upwards on the tendon of the temporal muscle; the other arises 
near the tuberosity of the upper maxillary bone: they are called 
the exterior deep, and the interior deep temporal artery. They 
are both spent upon the temporal muscle; but the interior branch 
sends a small twig into the orbit of the eye. 

f. There are some small branches which pass to the Ptery- 
goid Muscles and to the Masseter, which arises either from the 
internal maxillary artery, or from the interior deep temporal. 
They are generally small, and often irregular. 

o. An artery, particularly appropriated to the cheek, perforates 
the buccinator muscle from within outwards, and generally ter- 
minates on the buccinator, the zygomaticus major, and the mus- 
cles of the lips. This Artery of the Cheek is very irregular in its 
origin, sometimes arising from the internal maxillary, sometimes 
from the deep temporal, and sometimes from the suborbitary, or 
from the alveolar artery, to be immediately described. 

h. The Alveolar Artery or the Artery of the Upper Jaiv, arises 
generally from the internal maxillary, but sometimes from one 
of its branches. It winds round the tuberosity of the upper jaw, 
and sends branches to the buccinator muscle, to the bone and 
the gums, to the antrum Highmorianum, and some of the molar 
teeth : and also to the teeth generally, by means of a canal 
which is analogous to that of the lower jaw. 

i. The Infra erbiiar Artery arises from the internal maxillary 
in the zygomatic fossa, and soon enters the infra orbitary canal, 
through which it passes to the face, and emerges below the orbit 
of the eye, supplying the muscles in the vicinity, and anastomos- 
ing with the small ramifications of the two last described arteries, 
and also of the facial artery and the ophthalmic. 



232 INTERNAL MAXILLARY ARTERY. 

This artery in its course sends off small twigs to the perios- 
teum, the adipose membrane, and the muscles in the inferior 
part of the orbit, and also to the great maxillary sinus or antrum 
Highmorianum, and to the canine and incisor teeth. 

J. The Palato-Maxillary or Superior Palatine Artery, arises 
also in the zygomatic fossa, and, descending behind the upper 
maxillary bone, enters the posterior palatine canal. It generally 
forms two branches, the largest of which advances forward, sup- 
plying the palate and gums, and finally sends a twig through the 
foramen incisivum to the nose, while the posterior branch, which 
is much smaller, supplies the velum pendulum palati. 

k. The Pterygopalatine or Superior Pharyngeal, is a small 
vessel, which sometimes arises from the artery next to be men- 
tioned. It is spent upon the upper part of the pharynx, and a 
branch passes through the pterygo-palatine foramen, which is 
spent upon the arch of the palate and the contiguous parts. 

l. The Internal Maxillary at length terminates in the Spheno- 
palatine, or Lateral Nasal Artery, which passes through the 
spheno-palatine foramen to the back part of the nose. This ar- 
tery sometimes separates into two branches before it enters the 
foramen ; sometimes it enters singly, and divides into two 
branches soon after ; one of them is spread upon the septum, 
and the other upon the external side of the nose ; each of these 
branches ramifies very minutely upon the Schneiderian mem- 
brane and its processes in the different sinuses, and also in the 
ethmoidal cells. 

Distribution of the Internal Carotid, the Vertebral and Internal 
Maxillary Arteries, as seen upon making a vertical Section of 
the Head, (see Plate facing page 233.) 

a. The Upper Jaw Bone ; part of it is torn away. 

b. The Lower Jaw Bone ; all the angle of the right side is taken away, to 
show the internal maxillary artery. 

c. The Tongue. 

d. The Antrum Highmorianum, torn open. 

e. The Vertebra of the Neck, cut to show the passage of the artery, encased 
in the bones. 

f. f. The Skull-cap, sawn through exactly in the length of the longitudinal 






.,y. V. 












.^/.;< 







INTERNAL MAXILLARY ARTERY. 233 

g. The Falx, which divides the hemispheres of the Brain. 

h. The Longitudinal Sinus. 

i. The Fourth Sinus, returning the blood from the lower sinus of the falx, 

and from the vena galeni. 
k. Right Lateral Sinus. 

I. The Tentorium, which covers the cerebellum, and supports the posterior 
lobes of the cerebrum. 

Arteries. 

1. The Common Carotid Artery. 

2. The Internal Carotid Artery* 

3. The External Carotid Artery. 

4. The Vertebral Artery ; the processes of the vertebrae being cut away. 

5. The last and violent turn of the Vertebral Artery, before entering the 
foramen magnum of the occipital bone. 

6. The violent contortions of the Internal Carotid Artery, before entering 
the skull. 

7. The point of the Internal Carotid Artery, where, after making its turns 
in its passage through the bone, it appears by the side of the sella tur- 
cica. See Plate at page 243. 

8. The Ophthalmic Artery, derived from the carotid. It is this artery 
which is seen to inosculate with the Facial artery, in the preceding 
Plate, at page 228. 

9. The Thyroid Artery. 
10. The Lingual Artery. 

II. The Facial Artery cut short; it is seen in the Plate, at page 228, 
Fig. 2, passing over the jaw. 

12. The Continued Trunk of the External Carotid Artery; it is about to di- 
vide into the temporal and internal maxillary arteries. See the preceding 
Plate (11.) 

13. The Temporal Artery, cut short. 

14. The Internal Maxillary Artery. 

15. That Branch of the Internal Maxillary Artery, which passes into the 
lower jaw. 

16. The Great or Middle Artery of the Dura Mater ; a branch of the in- 
ternal maxillary, f 

* Internal Carotid. In Dr. Hooper's collection of preparations, there is a curi- 
ous example of the ulceration of this artery. A man intending to destroy himself, 
attempted to swallow pins tied together; they stuck in the pharynx, and in time 
penetrated to this artery, which suddenly cut him off. 

t It is this artery which rises through the spinous hole in the sphenoid bone, 
and then runs on the lower angle or spinous process of the parietal bone : here it 

20* 



234 INTERNAL CAROTID ARTERY. 

17. The Artery of the Upper Jaw. 

18. The Infra Orbital Artery ; it is seen to pass out upon the face. 

Fig. 2, is a Plan of the Internal Maxillary Artery. 

1. The Meningeal Artery, or great middle artery of the dura mater.* 

2. The Inferior Maxillary Artery.\ 

3. Irregular Arteries : the Pterygoid Arteries. 

5. The Deep Internal Temporal Artery. 

6. The Artery of the Cheek. 

7. The Artery of the Upper Jaw. 

8. The Infra Orbital Artery. 

9. The Upper Palatine Artery. 

10. The Origin of the Upper Pharyngeal Artery. 

The Internal Carotid Artery 

Is sometimes called the Artery of the Brain, as it is almost en- 
tirely appropriated to that viscus. 

From its origin to the commencement of its ramifications, the 
course of this blood-vessel is peculiarly tortuous. In conse- 
quence of which, the force of the blood in it is greatly diminished 
before it arrives at the brain. 

An instance of this curvature occurs immediately after its 
separation from the external carotid, when it protrudes outwards 
so much as to be exterior to that vessel ; after this it ascends to 
the carotid canal, and in its course is in contact, or very near the 
par vagum and intercostal nerves. 

The carotid canal in the os petrosum is by no means straight; 
it forms a semicircular curve, forwards and inwards; and its 
upper portion, which is nearly horizontal, opens obliquely against 

generally lies in a deep channel, and gives occasion to a kind of rule in surgery, to 
avoid applying the trephine at this part. 

* This artery enters the skull by the foramen spinale of the sphenoid bone, and 
is the same that makes the deep furrow in the inside of the parietal bone. Mr. 
Walker, of Edinburgh, communicated a case where an arrow shot into the skull 
wounded this artery. 

t Lower Maxillary. This artery enters at the posterior foramen of the lower 
jaw-bone, and courses within the bone, and appears on the chin, coming out 
through the mental foramen. In pulling the last molaris of the lower jaw, if the 
inner plate of the bone be broken off, and this artery torn up among the cells of 
the bone, the patient may die of bleeding. 



INTERNAL CAROTID ARTERY. 335 

the body of the sphenoidal bone, at a small distance from it. 
Therefore, after the artery has passed through the canal, it must 
turn upwards to get fairly into the cavity of the cranium ; and, 
of course, its direction while in the canal, forms almost a right 
angle with its direction before it enters, and after it emerges 
from it. 

In consequence of this curvature, much of the momentum of 
the blood must be impressed upon the cranium. 

After the artery has arrived at the end of the carotid canal, 
and has turned upwards to get within the cavity of the cranium, 
it bends forward;, and passes nearly in a horizontal direction, 
through the cavernous sinus on the side of the sella turcica, to 
the anterior clinoid process ; here it again forms a considerable 
curve, which is directly upwards, and then it perforates the dura 
mater. 

These curvatures must also deprive the blood of the carotid of 
a portion of the momentum which it has retained after leaving 
the bone. 

The object of these various flexures of the internal carotid 
appears' to be analogous to that of the Rete Mirabile in certain 
quadrupeds, which is formed by the division of this artery into 
many small branches, that reunite again, without producing any 
other effect than the diminution of the momentum of the blood. 

During its course from the place of bifurcation to its entrance 
into the carotid canal, the internal carotid artery very rarely 
sends off any branches. In the canal it gives off a small twig 
which enters the cavity of the tympanum; and sometimes a second, 
which unites with the Pterygoid branch of the internal maxillary. 

As it goes by the sella turcica, it passes through the cavernous 
sinuses, and gives off two branches, which are called the Pos- 
terior and Anterior Arteries of the Cavernous Sinus or Receptacle. 

The posterior branch goes to that part of the dura mater 
which is connected with the posterior clinoid process, and the 
cuneiform process of the occipital bone. It likewise gives 
branches to several of the nerves which are contiguous, and to 
the pituitary gland. 



236 



OPHTHALMIC ARTERY. 



The anterior artery also gives branches to the contiguous 
nerves, to the dura mater, and the pituitary gland. 

When the internal carotid turns upwards at the anterior clinoid 
process, it sends off the 

Ophthalmic Artery, 

Which passes under the optic nerve through the foramen 
opticum into the orbit of the eye, and is about a line and a half 
in diameter. 

Although this artery enters the orbit under the optic nerve, it 
soon takes a position on the outside of it, but afterwards gra- 
dually proceeds to the inner side of the orbit, crossing over this 
nerve in an oblique direction, and finally passes out of the orbit 
near the internal angle. In this spiral course it sends off nume- 
rous branches, viz. 

a. To those parts which are auxiliary to the eye. 

b. To the ball of the eye. 

c. To the cavity of the nose, through small foramina in the 
ethmoid bone, and 

d. To the forehead and external side of the nose. 
These branches generally go off in the following order : 

1. The Lachrymal Artery arises soon after the ophthalmic 
arrives within the orbit, and passes above the abductor muscle 
to the lachrymal gland, where it terminates, sending off many 
small branches in its course. 

2. The Central Artery of the retina also leaves the ophthalmic 
soon after its arrival in the orbit : it is a small vessel which pe- 
netrates into the centre of the optic nerve, and, passing with it 
into the eye, is spread upon the internal surface of the retina. 
Here it appears to terminate in the adult ; but in the foetus it is 
continued through the vitreous humour to the capsule of the 
crystalline lens. 

3. While the ophthalmic is passing over the optic nerve the 
branches which enter the ball of the eye leave it. Their number 
varies, but they form three classes, viz. The Long Ciliary, the 
Short Ciliary, and the Anterior Ciliary arteries, (see description 



OPHTHALMIC ARTERY. 237 

of the eye,) the supra orbitary and muscular branches leave it 
also near the same place. 

4. The Supra Orbitary Branch often gives off several muscular 
twigs : but it passes out of the orbit through the supra orbitar 
foramen, and generally divides into two branches, one of which 
is spent upon the periosteum, and the other upon the skin and 
muscles of the forehead. 

5. There are sometimes two muscular branches, a Superior 
and an Inferior. The superior branch is often deficient : when 
it exists it supplies the levator palpebrae, the levator oculi, ob- 
liquus superior, &c. ; but these parts are often supplied by the 
branches above mentioned. The supra orbitar so frequently 
gives off branches to the muscles, that it has been called the 
Superior Muscular Branch. The inferior muscular branch is 
more constant. It commonly supplies the rectus inferior, the 
abductor, and the inferior oblique muscles, and also the lachry- 
mal sac, and the lower eyelid, &c. 

When the artery is on the inside of the nerve it sends off the 
two branches to the cavity of the nose, viz. The Ethmoidal 
Arteries; and, also, branches to the eyelids. 

6. The Posterior Ethmoidal branch is first. It passes between 
the levator and abductor muscles, and above the obliquus supe- 
rior, and penetrates the cavity of the cranium by the posterior 
orbitary foramen : after giving some twigs to the dura mater, 
it passes to the posterior cells of the ethmoid by the foramina 
of the cribriform plate of that bone, and sends a small branch to 
the Schneiderian membrane on the back part of the septum of 
the nose. 

7. The Anterior Ethmoidal artery arises from the ophthalmic 
nearly opposite to the anterior orbitary foramen, through which 
it passes : and after entering the cranium is distributed like the 
other through some of the foramina of the cribriform plate to the 
anterior cells of the ethmoid bone, and to the anterior part of 
the Schneiderian membrane on the septum of the nose, to which 
it sends a considerable branch. 

In its course it sends twigs to the frontal sinuses, and to the 
dura mater and its falciform process. 



238 BRANCHES OF THE INTERNAL CAROTID TO THE BRAIN. 

8. The arteries of the Palpebrce are called Superior and In- 
ferior; they leave the ophthalmic near the loop or pulley of the 

superior oblique muscle. The inferior comes off first ; it sends 
branches to the ligaments of the tarsus, the caruncula lachryma- 
lis, and the parts connected with the cartilage of the under eyelid, 
and unites with the lachrymal artery near the external canthus, 
forming an arch called the Inferior Tarsal Arch. 

9. The Superior Artery supplies the superior part of the orbi- 
cularis muscle, the ligament and caruncula also: and it like- 
wise unites with a twig of the lachrymal, and forms the superior 
tarsal arch. 

Soon after sending off the palpebral branches, the Ophthalmic 
Artery arrives at the internal canthus, and then finally divides 
into two branches, the nasal and the frontal. 

10. The Nasal Branch passes above the superior part of the 
lachrymal sac, and the ligament of the eyelid to the nose; after 
sending a twig to the frontal muscle and the lachrymal sac, it 
passes down the side of the nose and anastomoses with the facial 
artery. 

11. The Frontal Artery is not so large as the nasal ; it gene- 
rally divides into three parts. A superciliary branch, which is 
principally spent upon the eyebrows ; a superficial branch, which 
is spent upon the forehead ; and a branch which is distributed to 
the pericranium. 

The Internal Carotid, soon after parting with the ophthalmic, 
sends off, in a posterior direction, a branch to join one from the 
vertebral artery. From its destination, this vessel is called the 
arteria communicans. 

After this it sends off another branch, which is so large that 
it may be considered as a continuation of the main trunk : this 
is called the middle artery of the brain, or the Arteria Sylviana. 
It runs outwards nearly in the direction of the fossa Sylvii, 
which separates the anterior from the middle lobes of the cere- 
brum. In its course it divides and subdivides into numerous 
branches, which are spread upon the Pia Mater, and finally enter 
the surface of the brain in a very minute state. 

The internal carotid then terminates in a branch, which is 



RIGHT AND LEFT SUBCLAVIAN ARTERIES. 2,39 

smaller than the last mentioned, and from its situation is called 
the Anterior Artery of the Brain, or Arteria Callosa. This vessel 
first inclines towards its fellow on the opposite side, and after 
approaching within half an inch of it, forms another curve, and 
runs forward to the anterior part of the brain, dividing itself gra- 
dually into two branches, which pass in several directions. 

When these anterior arteries are nearest to each other, a small 
transverse branch, which passes at right angles, connects them 
together. This branch completes the anterior part of the Circle 
of Willis. 

It crosses immediately before the sella turcica and pituitary 
gland, and sends off branches which pass to the third ventricle, 
to the fornix and septum lucidum, and also to the pia mater. 

The Anterior Arteries of the brain also send off branches to 
the optic and olfactory nerves ; to the opposite surfaces of the 
two hemispheres on each side of the falx, to their inferior sur- 
faces, and to the corpus callosum. 

They have likewise some branches which anastomose with 
those of the middle artery of the brain, and of the vertebral 
artery. 

The Subclavian Arteries. 

The Right Subclavian may be considered as the continuation 
of the arteria innominata. This last mentioned artery, after 
leaving the aorta, forms a curve or arch, which extends obliquely 
backwards and outwards, over the first rib to the axilla, crossing 
the trachea in its course. At the distance of an inch and a quar- 
ter, or an inch and a half from its origin, it sends off the right 
carotid, and then, assuming the nnme of Right Subclavian, con- 
tinues in the above stated direction.- 

The chord of the curve of this artery, and the chord of the 
curve of the aorta, are not in the same direction, but form an 
angle with each other. 

The position of the Left Subclavian is somewhat different 
from that of the right. Its origin is posterior, and, therefore, the 
direction of the chord of its curve is more immediately lateral. 
The curve or arch is also smaller. The situation of the two 



240 



INTERNAL MAMMARY ARTERY. 



subclavians as relative to the contiguous parts, is, therefore, some- 
what different ; but each of them proceeds between the anterior 
and the middle scaleni muscles, and when they have arrived at 
these muscles, their respective positions are very similar. 

The anterior and middle scaleni muscles arise from the trans- 
verse processes of several of the cervical vertebras, and are in- 
serted into the first rib, one before the other, so as to leave a 
considerable space between them. The subclavian arteries pass 
through this space, but before they arrive at it, and when they 
are very near the above mentioned muscles, they send off several 
very important branches in various directions, viz. to the cavity 
of the cranium, to the parietes of the thorax, to the thyroid 
gland, and to the lower part of the neck. 

They proceed near to the scaleni muscles before they send off 
any branches ; and it is to be observed, that the subclavian veins 
which correspond with these arteries, are anterior to them, 
for they pass before the scaleni muscles, and not between them. 

The Internal Mammary Artery 

Goes downwards, from the lower and anterior part of the 
subclavian, along the inner side of the anterior scalenus muscle. 
It proceeds, exterior to the pleura, across the carriages of the 
true ribs, and near their middle; and, continuing between the 
cartilages and the diaphragm, exterior to the peritoneum, termi- 
nates on the rectus abdominis muscle, in branches which anas- 
tomose with those of the epigastric artery. In this course, it 
gives branches to almost all the parts to which it is contiguous, 
viz. to the muscles and glands at the lower part of the neck; to 
the thymus gland ; to the parts in the intercostal spaces ; to the 
sternum; to the mediastinum and pericardium; to the diaphragm 
and to the muscles of the abdomen. 

From some of its ramifications upon the parts between the 
ribs, small branches go off to the mamma, and thereby give a 
name to the artery. There is also a small vessel which is sent 
off by the mammary artery, or by one of its upper branches 
which accompanies the phrenic nerve to the diaphragm. 



THYROID AND VERTEBRAL ARTERIES. 



241 



The Inferior Thyroid Artery 

Arises from the upper side of the subclavian nearly opposite 
to the origin of the internal mammary. It passes upwards and 
inwards, between the carotid artery and the spine, to the thy- 
roid gland : and then it anastomoses with the branches of the 
superior thyroid on the same side, and with those of its fellow on 
the opposite side. 

This vessel sometimes sends off large branches to the muscles 
at the lower part of the neck. 

The Vertebral Artery 

Arises from the upper and posterior part of the subclavian. 
It goes upwards and backwards between the muscles which lie 
on the front of the spine, and passing under the transverse pro- 
cess of the sixth or seventh cervical vertebra, enters into the 
canal formed in the transverse processes of the vertebra?. In 
this course, as il proceeds from the third to the second cervical 
vertebra, it inclines outwards laterally, and, in its passage from 
the transverse process of the second to that of the first vertebra, 
it forms a considerable curve, the convexity of which has a 
lateral and external aspect. After passing the transverse pro- 
cess of the Atlas, it is turned suddenly backwards, in a groove, 
and finally passes through the great occipital foramen into the 
cavity of the cranium. It then proceeds upon the cuneiform 
process of the occipital bone, under the Medulla Oblongata, and 
joins its fellow so as to form an acute angle with it near the 
union of the medulla oblongata with the pons Varolii. From 
each of the vertebral arteries before their union, there generally 
goes off a small branch called the Posterior Meningeal, which is 
spent upon the posterior part of the dura mater. 

The trunk formed by the union of the vertebral arteries is 
called 

The Basilar Artery. 

It extends forward near to the anterior part of the pons Va- 
rolii, where it bifurcates ; but previously sends off several 
vol. ii. 21 



242 ARTERIES OF THE BRAIN. 

branches on each side. The first pair go off in a lateral direc- 
tion, soon after its commencement, near the back part of the 
pons Varolii, and are spent upon the medulla oblongata, the pons 
Varolii, and the other contiguous parts, and also upon the fourth 
ventricle and the Plexus Ckoroides of that cavity. They are 
called the Posterior or Inferior Arteries of the Cerebellum. 

Two other lateral branches, which are called the Superior 
Arteries of the Cerebellum, go off from the Basilar artery, near 
its anterior extremity. These are principally spent upon the 
crura of the cerebellum and cerebrum : upon the cerebellum 
itself, and the contiguous parts. 

Soon after sending off the last mentioned arteries, the Basilar 
artery divides into two branches, which also take a lateral di- 
rection, and are of considerable size. In their course outward, 
these branches are curved with their convexity forward. About 
ten or twelve lines from its commencement, each of them sends 
off a branch called the Arteria Communicans, which passes 
directly forward, and communicates with the internal carotid, 
thus forming the arrangement which is called the Circle of 
Willis.* After sending off these arteries, they continue their 
lateral direction, and are distributed principally to the posterior 
parts of the cerebrum. These terminating branches of the Ba- 
silar Artery, are called the Posterior Arteries of the Cerebrum. 

Arteries of the Brain, which are derived from the Internal Ca- 
rotid and Vertebral, {see Plate facing page 243.) 

a. a. The Anterior Lobes of the Cerebrum. 

b. b. The Middle Lobes of the Cerebrum. 

v. c The Posterior Lobes of the Cerebrum, which rest upon the tentorium. 
d. The Right and Left Lobes of the Cerebellum. 

* The arteria communicans is also considered as a branch of the Internal Ca- 
rotid. The arrangement here alluded to is very remarkable. As the branches 
which pass offlaterally from the single trunk of the Basilar Artery are united to the 
Internal Carotids, and the Internal Carotids are united to each other, there is an 
uninterrupted continuation of artery, which encloses a portion of space of a de- 
termined form; but this form resembles an oblong square more than a circle. By 
this connexion, blood will pass from any one of the four arteries of the brain to all 
the others. 






t : /■>'.// ./,/. 






SUPERIOR INTERCOSTAL ARTERY. 



243 



e. The Medulla Oblongata. 

f. The Optic Nerves, cut at their union. 

g. The Corpora Albicantia ; the Infundibulum is seen betwixt these and 
the optic nerves. 

h. h. The Crura Cerebri. 

i. The Pons Varolii, or Tuberculum Annulare. 

k. The Eminences of the Medulla Oblongata, called Corpora Pyramidalia. 

I. The Corpora Olivaria. 

Arteries. 

1. 2. The Right and Left Carotid Arteries, raised with the brain, and cut 
off as they rise at the point marked in the preceding Plate; that is, as 
they rise at the side of the sella turcica. 

3. 4. The Right and Left Vertebral Arteries. 

5. The Union of the Vertebral Arteries to form the Basilar Artery. 

6. The Communicating Artery, or Anastomosis, betwixt the Basilar Artery 
and Carotid. 

7. The Union of Communication betwixt the carotids of each side by the 
anterior arteries of the cerebrum ; these anastomoses 6 and 7 form the 
Circle of Willis. 

Divisions of the Internal Carotid Artery. 

8. The Middle Artery of the Brain passing into the Fissura Silvii. 

9. The Anterior Artery of the Cerebrum. 

Branches of the Vertebral and Basilar Arteries. 

10. The Posterior Artery of the Cerebellum from the Vertebral Arteries. 

II. A very considerable branch of the Basilar Artery to the pons varolii and 
cerebellum, which, however, has no name. 

12. The Anterior Artery of the Cerebellum. 

13. The Posterior Artery of the Cerebrum. 

The lesser branches of vessels seen in this Plate are mentioned in the text, 
but are not distinguished by any particular name. 

The Superior Intercostal Artery 

Arises from the upper part of the Subclavian, after the Ver- 
tebral and Thyroid arteries, and very near them. It descends by 
the side of the spine across the first and second ribs, near their 
heads, and exterior to the great intercostal nerve. It generally 
forms two branches, which are appropriated to the muscles, &c. 
in the first and second intercostal spaces, and sometimes a small 



244 CERVICAL ARTERIES. 

branch is continued to the third intercostal space. From each 
of these branches a small vessel proceeds backwards, and is 
spent upon the contiguous muscles, &c. on the back of the thorax. 
The Intercostal Artery also sends a branch upwards to the deep- 
seated parts of the neck. 

In addition to the arteries above mentioned, there are several 
others of considerable size which originate either directly or 
indirectly from the Subclavian, and are spent upon the lower 
portion of the neck and the contiguous parts. These arteries 
are very different in different subjects, especially as to their origin. 
Two of them, which have been called the Anterior and Posterior 
Cervicals, are generally distributed to the muscles and other 
parts which lie on the lower portion of the neck anteriorly and 
posteriorly. 

A third, which passes transversely on the lower part of the 
neck, is called the Superior Scapular. 

In some cases, the two Cervical Arteries arise from the sub- 
clavian, after the mammary and the thyroid, in a common trunk, 
which soon divides. Very frequently they go off from the In- 
ferior Thyroid. Sometimes one of them goes off from the Inferior 
Thyroid and the other from one of the branches of the Sub- 
clavian.* 

The Superior Scapular most commonly arises with some other 
artery, and very often from the Inferior Thyroid. It runs trans- 
versely outwards within and above the clavicle, and passing 
through the notch in the upper costa of the scapula, divides into 
branches which are distributed to the parts on the dorsum of 
that bone. 

The Subclavian Artery, in its progress from the aorta to the 

* Haller paid great attention to the arterial system, and made many dissections, 
with a view to engravings of it, which he published with descriptions in folio 
fasciculi. 

These fasciculi have been collected, and, with some other engravings, form a 
large volume, entitled icones anatomic*, which is truly valuable. 

There arc some very interesting observations on this work of Haller's, and also 
on these arteries, in a description of the arteries, by Dr. Barclay, of Edinburgh, 
which I have read with advantage, as well as a work on the muscles by the same 
author. 



SUBCLAVIAN AXILLARY. 245 

axilla, forms an arch or curve, over the fifth rib, as has been 
already observed. The anterior scalenus muscle is before it, 
and the great nerves of the upper extremity are above it. After 
passing between the scaleni, it descends upon the first and second 
rib into the axilla. The nerves which are above descend with 
it; at first they are necessarily exterior to it; but they form a 
plexus which the artery enters into, so as to be partly surrounded 
by them. This course of the artery is obliquely under the cla- 
vicle, and behind the pectoral muscle. In the axilla, the vessel 
and nerves which surround it are placed between the tendons of 
the pectoralis and the latissimus dorsi muscles. Here the artery 
takes the name of Axillary, and sends off several important 
branches. 

The principal branches that go off from the axillary artery 
are distributed, 

1st. Anteriorly, to the pectoral muscle, and the parts on the 
anterior surface of the thorax. 

2d. Posteriorly to the muscles which are on the scapula and 
contiguous to it ; and 

3d. To the parts which are near the upper extremity of the os 
humeri. 

Anterior Branches, 

The arteries which go to the pectoral muscle, &c. are very 
various in different subjects, both as to their number, origin and 
size. 

They have been called by different names, as Thoracicce Ex- 
terna, Mammarice Externa, &c. 

There are almost always three of them, and very often more: 
one of them, which is called by several authors the Acromialis, 
proceeds towards the end of the clavicle, and generally passes 
out at the interval between the deltoid and the pectoral muscle, 
sending various branches to the contiguous parts ; the largest of 
its branches often passing in the direction of the interstice be- 
tween those muscles. 

Another of these arteries, which is called Superior Thoracic, 

21 * 



246 BRANCHES OF THE AXILLARY ARTERV. 

is generally very small : it often is a branch of the above men- 
tioned Acromialis. 

There is very often to be found here an artery called the In- 
ferior Thoracic, or the External Mammary, which is of consider- 
able length, although its diameter is not very great. This artery 
originates near the two last mentioned, and sometimes from the 
Acromialis. It often extends downwards as low as the sixth rib, 
and sends branches to the anterior part of the thorax, to the 
mamma, and other contiguous parts. Many of the small 
branches of this artery anastomose very freely with those of 
the internal mammary. 

There are always one or more small arterial branches in the 
axilla, which ramify upon the glands and adipose matter always 
existing there. They often arise by one common trunk, which 
is called the Thoracica Axillaris. 

Posterior Branch. 

One large artery is commonly sent to the muscles on the sca- 
pula, which is called the Scapular, the Common Scapular, or the 
Internal Scapular. It commonly passes off from the axillary 
after the thoracic arteries, and supplies the muscles on both sur- 
faces of the scapula. This large vessel passes downwards a 
short distance in the direction of the inferior costa of the sca- 
pula, and soon sends off a branch that winds round to the dorsum 
of the bone, to be distributed to the infra spinatus and the con- 
tiguous muscles, which is called the Dorsalis Scapulce. The 
main trunk then inclines to the subscapulars muscle, and ge- 
nerally divides into two branches, which are distributed to the 
subscapularis, teres major, latissimus dorsi, &c. 

Sometimes the Scapular artery divides into two branches be- 
fore it sends off the dorsal. In this case the last mentioned 
artery goes off from one of those branches. 

Branches near the Os Humeri. 

The arteries which are near the body of the os humeri, at its 
upper end, are generally two in number, and denominated the 
Anterior and Posterior Circumflex. Sometimes they arise sepa- 



HUMERAL ARTERY. 247 

rately, and sometimes in a common trunk from the axillary 
artery. Frequently, one of them arises from the scapular. 

The Anterior Circumflex passes between the united heads of 
the biceps and coraco-brachialis muscles and the body of the os 
humeri, at a small distance below its head. It sends branches 
to the capsular ligament, the periosteum of the os humeri, the 
membranes of the groove for the long head of the biceps, the 
upper portions of the biceps and coraco-brachialis, and some 
contiguous muscles. 

The Posterior Circumflex proceeds between the subscapularis 
and teres major muscles, and continues between the os humeri 
and the head of the triceps and the deltoides. It is distributed 
to the muscles and parts about the joint, especially to the del- 
toides. 

These arteries surround the os humeri, and the small branches 
anastomose with each other. The Posterior Circumflex is much 
larger than the Anterior. 

The great artery of the arm proceeds from the axilla to the 
elbow; and, during this course is generally denominated. 

The Humeral Jlrtenj* 

Its direction is influenced by the position of the os humeri. 
When the arm hangs down, with the palm of the hand present- 
ing forward, this direction is somewhat spiral. The situation of 
the artery is on the inside of the biceps muscle, and between 
that muscle and the triceps extensor. It also continues very 
near and on the inside of the tendon of the biceps, and under the 
Aponeurosis which proceeds from that tendon. In consequence 
of the spiral or oblique course of the artery, its direction would 
be from the inside of the tendon of the biceps to the radial side 
of the fore-arm ; but soon after it passes across the joint of the 
elbow, it divides into two branches: one which preserves, for 
some distance, the direction of the Main Trunk, is called the 
Radial artery: the other, which inclines obliquely downwards 
and towards the ulna, is the Common Trunk of the Ulnar and 
Inter osseal Arteries. 

* It is called the Brachial Artery by several writers. 



248 BRANCHES OF THE HUMERAL ARTERY. 

During this course, the Humeral artery sends off several 
branches to the muscles and other parts on the os humeri. The 
largest of them is denominated the Profunda Humeri or Spiralis. 
This artery very often arises as high as the insertion of the latis- 
simus dorsi, and passing between the heads of the triceps exten- 
sor muscle, proceeds downwards under that muscle in a spiral 
direction, towards the external or radial condyle. It sends se- 
veral branches to the triceps and the contiguous muscles, and 
one considerable branch, which is generally called the Profunda 
Minor, to the parts contiguous to the internal condyle. The rami- 
fications of these branches near the condyle frequently anasto- 
mose with small branches of the radial and ulnar arteries.* 

A small branch frequently arises from the Humeral artery, at 
a short distance from the Profunda Humeri, which sends a rami- 
fication to the medullary foramen of the os humeri. This vessel 
is, therefore, denominated Arteria Nutritia. 

There are very often several anastomoses between the branches 
of the Humeral artery which originate above the elbow, and cer- 
tain branches of the Radial and Ulnar arteries which are 
called, from their direction, recurrents. Among these arteries 
there is generally one of considerable size, which proceeds 
across the elbow joint near the internal condyle. Sometimes 
this is the ulnar recurrent, which goes up to anastomose with the 
branches of the profunda ; but more frequently it is a separate 
branch of the Humeral artery which goes off a little above the 
elbow, and passes across the articulation, near the internal con- 
dyle, to anastomose with the branches of the ulnar artery. This 
artery is denominated the Anastomotica. 

There are often other branches sent off by the Humeral arte- 
ry ; but they are commonly small, and very irregular. 

The two great ramifications of the Humeral artery on the 
fore-arm have very different directions. The Radial artery pre- 
serving the course of the main trunk while the Common Trunk 
of the Ulnar and Interosseal projects from it in a direction down- 

* The profunda sometimes originates from the scapular, or one of the circumflex. 
The profunda minor sometimes has a distinct and separate origin, lower down than 
the other. 



RADIAL ARTERY. 249 

wards and towards the ulna, passing under the pronator teres, 
&c. 

The Radial Artery, 

Passing over the pronator teres muscle, proceeds between the 
supinator radii longus and the flexor carpi radialis, very near 
to the lower end of the radius, without changing its direction 
materially, being deep-seated above and superficial below; it then 
alters its course, and, passing under the tendons of the extensors 
of the thumb, to the back part of the radius, it continues between 
the metacarpal bones of the thumb, and of the index finger, when 
it divides into three branches. 

In this course, it gives off but few branches. The first is the 
Radical Recurrent, which passes upwards and towards the ex- 
ternal condyle, but frequently anastomoses with the ramifications 
of the profunda humeri. 

The branches which it sends off between the origin of the re- 
current and the lower end of the radius, are generally very small, 
and distributed to the parts immediately contiguous to the ar- 
tery. Before it turns under the tendons of the extensors of the 
thumb, it sends a branch over the wrist towards the root of the 
thumb, from which proceeds a branch to anastomose with the 
volar branch of the ulnar ; and another, not so large, which is 
frequently continued on the radial or external side of the thumb, 
very near to its extremity. While the radial artery is under the 
aforesaid tendons, it sends off small branches to the back of the 
wrist and back of the hand, and often to the back of the thumb. 
Those which are distributed to the wrist and back of the hand, 
generally anastomose with the small branches of the ulnar and 
interosseal arteries. 

The three branches into which the radial artery divides be- 
tween the metacarpal bones of the thumb and index are, 1st, a 
branch to the external side of the index ; 2dly, a branch to the 
thumb, that sometimes divides into two, which pass up on the 
anterior or volar surface, and sometimes continue, without much 
diminution, on the internal side of the thumb, near to the end of 
the last phalanx ; and, 3dly, a branch, called Palmaris Profunda, 



250 ULNAR ARTERY. 

which dips down into the palm of the hand, and proceeding in 
contact with the metacarpal bone, under the flexor tendons, &c. 
forms an arch which extends across the hand, and often termi- 
mates by anastomoses with another arch, soon to be described, 
which is formed by the ulnar artery. 

This flexure, which is denominated Arcus Profundus, sends off 
branches of a very small size, which are distributed to the bones, 
ligaments, muscles, &c, contiguous to it. 

The Common Trunk of the Ulnar and Interosseal Arteries 

Passes under several of the muscles which originate from the 
internal condyle, and between the flexor sublimis and the flexor 
profundus. Before the Ulnar Recurrent goes off from this ves- 
sel, the interosseal artery often leaves it. This recurrent artery 
passes upwards between the muscles of the internal condyle, 
and distributes branches among them. It then passes up in the 
groove behind the internal condyle, and anastomoses with the 
branches of the Anastomotica or Profunda Humeri. 

The ulnar and interosseal arteries separate from each other at 
the distance of fifteen or twenty lines from the origin of the 
radial artery, very near the commencement of the interosseal 
ligament. 

The Interosseal Artery, 

In a majority of cases, arises in a single branch from the com- 
mon trunk of the ulnar and interosseal. When it does so, the 
single branch soon sends off the Posterior Interosseal artery, 
which perforates the interosseous ligament, and passes down on 
its posterior surface, while the main branch continues on the an- 
terior surface of the ligament, and is denominated the Anterior 
Interosseal Artery. In some cases, the main branch proceeds on 
the anterior surface as low as the upper edge of the pronator 
quadratus muscle, before it sends off the posterior branch. Some- 
times the anterior and posterior interosseals arise separately. In 
this case the posterior soon perforates the ligament. 

The Anterior Interosseal passes down almost in contact with 
the ligament, and gives branches to the contiguous parts in its 



ULNAR ARTERY. 25J 

course. It generally perforates the interosseous ligament near 
the wrist, and sends off many small branches to the back of the 
wrist and hand, which anastomose with the small branches of 
the radial and the posterior interosseal arteries. 

The Posterior Interosseal soon gives off a recurrent or anasto- 
mosing branch, and then proceeds downwards towards the 
wrist, sending branches in its course to the extensor muscles 
and tendons. 

This vessel sometimes divides into two branches. 

The Ulnar Artery. 

The Ulnar artery proceeds among the muscles obliquely down- 
wards, and is not superficial until it has arrived within three or 
four inches of the carpus: it then continues towards the hand, 
sending off very small branches in its progress. It passes over 
the annular ligament at the wrist, and winds round the pisiform 
bone: here it is supported by a delicate ligament, which seems to 
lie upon it: from this it passes upon the palm of the hand, under 
the aponeurosis palmaris, and over the tendons of the flexors of 
the fingers. When thus situated, it forms, in perhaps a majority 
of subjects, an arch or bow, called Arcus Sublimis, w hich ex- 
tends across the palm of the hand, from the ulnar towards the 
radial edge, and, after sending branches to the fingers, &c. from 
its convex side, terminates near the root of the thumb, by anas- 
tomoses with that important branch of the radial artery, which 
passes up on the inside of the thumb. The Arcus Sublimis almost 
always sends off small branches, to the integuments, &c. on the 
palm of the hand. It often sends off, near the root of the meta- 
carpal bone of the little finger, a branch which passes between 
the flexor tendons and the metacarpal bones, and anastomoses 
with the Arcus Profundus. It then generally sends off a branch 
to the inner or ulnar side of the little finger; and afterwards 
three branches in succession, which pass from its convex side 
towards the angles formed by the fingers. These are called 

The Digital Arteries. 
When they have arrived near to the heads of the first pha- 



252 



ARTERIES OF THE ARM. 



langes of the fingers, each of these arteries divides into two 
branches, one of which passes along the side of one of the fingers 
to its extremity, and the other on the opposite side of the next 
finger : and in this way they pass on the sides of all the fingers, 
except the inside of the little finger, and the outside of the index. 
These branches of the digital arteries are called Digito-Radial 
and Digito-Ulnar arteries, according to the sides of the fingers 
on which they are placed. They are situated on the angle, 
if it may be so termed, which is formed by the anterior and la- 
teral surfaces of each finger. In their course from the basis to 
the extremity of the finger, they send off very small transverse 
branches, which anastomose with each other, especially near the 
other. Some transverse branches are observable on the posterior 
as well as the anterior surface. Near the extremity of each 
finger, beyond the insertion of the flexor tendon, the extremities 
of these arteries ramify minutely. Some of these small branches 
go to the skin, and others anastomose with their fellows of the 
opposite side. Some also go to the back of the fingers.* 

Of the Arteries of the Arm, (see Plate facing page 253.) 

a. The Scapula. 

b. The Pectoral Muscle held up. 

c. The Deltoid Muscle. 
». The Biceps Muscle. 

e. The Coraco-brachialis Muscle. 

f. The Triceps extensor Muscle. 

* The distribution of the radial and ulnar arteries in the hand, is very different 
in different subjects. 

Upon examining a large number of injected preparations in Philadelphia, it was 
found that, in a very small majority of them, the ulnar artery formed an arcus 
sublimis, whose branches extended as far as the ulnar side of the index, and some- 
times beyond it. 

That, in near a third of the preparations, the ulnar artery ramified without 
forming an arcus, and supplied only two of the digital branches, viz. the first two 
on the ulnar side. In such cases the radial artery generally made up the de- 
ficiency of the ulnar, but in a few instances the interosseal was extended on the 
palm of the hand, and supplied the radial side of the middle finger and the cor- 
responding side of the index. 

In a few instances also the ulnar artery was still more deficient, and the radial 
was proportionally extended. 












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BRANCHES OF THE SUBCLAVIAN AND AXILLARY. 253 

0. The Teres Major. 

h. The Tendon of the Lesser Pectoral Muscle. 

i. The Supinator Longus. 

K. The Extensor Carpi Radialis. 

1. The Flexor Carpi Ulnaris. 

if. The PaJmaris Longus and Flexor Muscles of the Fingers. 

From the Aorta till the Artery passes over the first rib, it is called, 

1. The Subclavian Artery. When this artery is injected, and tolerably full, 
it makes two pretty acute turns, in the form of an italic S, before it es- 
capes under the clavicle. Its larger curve is just where it comes through 
the anterior and middle portions of the Scalenus muscle. It then descends 
directly across the first rib. It then comes out under the clavicle, three 
fingers' breadth from the inner extremity of the clavicle. Just at this 
point, viz. where it passes over the bulging of the rib, it may be compress- 
ed in the living body. Its branches are, 

2. The Internal Mammary Artery.* 

3. The Vertebral Artery. 

4. The Thyroid Artery. 

5. The Ascending Thyroid Artery, a branch of the last. The Transver- 
salis Colli, or Cervicalis Posterior, is also generally a branch of the 
Thyroid, very irregular in its origin. Sometimes it comes from the 
Thyroid, and then receives the name of Transversalis Humeri ; 
sometimes it comes from the place of the Cervicalis Superficialis, or 
even from the Subscapulars ; sometimes from the Subclavian itself. 
The Deep and Superficial Cervical Arteries. 

6. The Supra Scapular Artery. 
The Axilla. 

7. The Trunk now assumes the name of Axillary Artery. Its branches 
are three or four to the chest ; three to the scapula and shoulder. 

8. The Lesser Superior Intercostal Artery, or Superior Thoracic Artery. 

9. The Greater or Longer Thoracic Artery, or External Mammary 
Artery. 

10. The Thoracica Acromialis, or Humeraria. 

The Thoracica Axillaris is not seen in this subject. 

11. The Subscapular Artery ; it is seen to divide upon the edge of the 
Scapula, into a deeper and a more superficial branch. 

* Branches of the Internal Mammary Artery. 1. To the Thymus. 2. Accom- 
panying the Phrenic Nerve. 3. To the Pericardium. 4. To the Mediastinum 

5. Several branches to the Pectoral Muscle and Mamma. 6. To the Diaphragm. 
7. To the Abdominal Muscles, inosculating with the Epigastric Artery. If a 
thrust be made with a small sword in any part (below the second rib) in a line pa- 
rallel with the Sternum, and three-fourths of an inch from its edge, it will wound 
the Internal Mammary Artery. 

vpL. ii. 22 



254 BRANCHES OF THE BRACHIAL OR HUMERAL ARTERY. 

12. The Posterior Circumflex Artery of the arm. 

13. The Anterior Circumflex Artery of the arm. 
In the Arm. 

14. The Trunk now assumes the name of Humeral Artery ; it gives oft' 
these branches : 

15. The Superior, or Greater Profunda. 

16. The Lesser Profunda. 

17. The Anastomoticus Major ; the lesser anastomosing branch comes off 
higher up, and follows the same direction round the inner condyle. 

Arteries of the Fore- Arm. 

Extremity of the Humeral Artery. The Artery divides three-fourths 
of an inch below the part of the Median Basilic Vein, where we 
generally bleed. 

18. 18. The Radial Artery. 

19. 19. The Ulnar Artery. 

The Interosseous Artery, which divides into the Inner and Outer 
Interosseous. 
The Recurrent Arteries from these last are, the 
Recurrens Radialis Anterior. 
Recurrens Ulnaris Anterior. 
Recurrens Ulnaris Posterior. 
Recurrens Interossea. 

20. At this point the Radial Artery turns under the supinator tendon and 

extensor tendons of the thumb. 
Superficial Artery of the Palm. 

21. The Ulnar Artery passing over the wrist. 
Dorsalis Ulnaris. 

Arteria Palmaris Profunda Ulnaris. 

22. The Great Palmar Arch, from which the Arteries of the fingers are 

seen to proceed. 

23. This dotted line marks the seat of the Lesser Arch under the tendons. 

FIG. II. 

From this sketch of the arteries we can follow in idea their continued course 
among the muscles. 

Termination of the Radial Artery as seen on the Plate opposite, 

(from Bell.) 

a. Arteria Radialis. 

b. Ramus Dorsalis. 

c. Palmaris Profunda. 

d. Ramus ad Indicem. 
k. Ramus ad Pollicern. 



i 







BRONCHIAL AND (ESOPHAGEAL ARTERIES. 255 

Of the Branches which go off between the Arch and the great 
Bifurcation of the Aorta. 

PART I. 

In the Cavity of the Thorax. 

The aorta sends branches to the Lungs, to the oesophagus, and 
to the parietes of the thorax. 

The Bronchial Arteries 

Are the vessels which go from the aorta to the ramifications 
of the trachea, and the substance of the lungs. They are not 
large, and are very irregular as to number and origin. 

In a majority of cases the right lung is supplied, in part, by a 
branch from the first aortic intercostal of that side ; while the 
left lung receives two or three branches from the aorta directly. 
In some cases a large vessel arises from the aorta, which divides 
into two branches, one of which goes to each lung. 

The Bronchial arteries frequently send small branches to the 
posterior mediastinum, the pericardium, &c. 

Injections have shown, that there is a direct communication 
between these vessels and the branches of the pulmonary artery. 

The (Esophageal Arteries 

Are very small vessels, which generally arise from the aorta, 
but sometimes are branches of the bronchials or intercostals 
that are spent upon the oesophagus. They occur in succession, 
and sometimes are five or six in number. They also send twigs to 
the contiguous parts, and the lowermost often descend to the 
stomach. 

The Inferior Intercostals 

Are the arteries which proceed directly from the aorta to the 
parietes of the thorax. Their name is derived from their position 
between the ribs. They are ramified on the intercostal muscles 
and ribs, and on the pleura and some of the contiguous parts. 



256 INTERCOSTAL ARTERIES. 

They are called Inferior or Aortic Intercostals, to distinguish them 
from the superior intercostals, which are derived from the sub- 
clavian artery. Their number varies from ten to eight, ac- 
cording as the superior intercostals are more or less numerous. 

They originate in pairs on the posterior surface of the aorta. 
The uppermost of them pass obliquely upwards, and the lower- 
most nearly in a horizontal direction, to the lower edges of those 
ribs to which they are appropriated. They meet the rib near 
its tubercle, or place of junction with the transverse process of 
the vertebra, and then proceed forward, between the internal 
and external intercostal muscles, in a superficial but large groove, 
which is generally to be found on the interior margin of the 
lower surface of the rib.* There is necessarily a difference in 
the length of the right and left intercostals, owing to the position 
of the aorta, which is rather on the left of the spine. In con- 
sequence of this circumstance, the oesophagus is anterior to, and 
also in contact with those of the right side. 

They generally send off an important branch, called the 
Dorsal, which arises near their origin, and, passing backwards, 
sends ramifications to the muscles of the back. From this 
dorsal branch also proceeds a ramification, which enters the 
spinal cavity, and is spent upon its membrane and upon the 
medulla spinalis. 

After the Intercostals in their progress forward, have passed 
beyond the middle of the ribs, they send off a branch, which 
generally proceeds very near to the upper side of the lower rib. 
The main trunk generally leaves the lower edge of the rib when 
it has arrived within one-third of the length of the bone from 
its anterior extremity. It then generally divides into several 
branches, some of which are spent upon the pleura, and others 
on the intercostal and the contiguous muscles. 

According to the situation of the different intercostals, some 
of their ramifications, communicate with those of the internal 
and external mammaries, of the phrenic, the lumbar, or the epi- 
gastric arteries. 

* See Vol. i. page 136. 



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BRANCHES OF THE AORTA IN THE CAVITY OF THE ABDOMEN. 257 

PART 2. 

In the Cavity of the Abdomen. 

The Aorta passes into the cavity of the abdomen between the 
crura of the diaphragm, as has been already mentioned. In its 
course from the crura to its great bifurcation, it sends off one 
pair of small arteries, called Phrenic, to the diaphragm. Three 
single arteries, the Casliac, the Superior, and the Inferior mesen- 
teric, to the viscera of the abdomen. A pair of large arteries, 
the Emulgents, to the kidneys, with several that are very small 
to their appendages ; as the Spermatics, Capsular, the Ureteric, 
and the Adipose. In addition to these, there is one pair of small 
arteries that go to the testicles, or to the ovaria and the uterus, 
and four or five pair, called Lumbar Arteries, that go off la- 
terally, like the intercostals, to the parietes of the abdomen, and 
to the muscles, &c. on the back, which are contiguous to them. 

Representation of the Diaphragm, the Situation of the Heart, the 
Blood-vessels of the Breast, and Abdominal Aorta. (See Plata 
facing page 257.) 

a. The Diaphragm, dividing the thorax from the abdomen. 

b. The Heart, lying upon the diaphragm, and with the apex obliquely to the 
left side. 

c. The Right Auricle. 

d. The Left Auricle ; that which receives the blood from the lungs. 

e. The Superior Vena Cava, returning the blood from the arms and head to 
the right auricle. 

f. The Arch of the Aorta. 

g. The Pulmonary Artery. 

h. h. The Right and Left Carotid Artery. 

i. The Subclavian Artery. 

s. The Internal Mammary Artery. 

h. The Thyroid Artery, to the shoulder, the neck, and the thyroid gland. 

h. The Vertebral Artery. 

n. The Lungs of the right side. 

o. The Perforation of the Diaphragm, for the transmission of the inferior 

cava, 
p. The Hole by which the (Esophagus passes into the abdomen. 
H. The Lesser Muscle of the Diaphragm. See the text, p. 312, Vol. i. 

22* 



258 PHRENIC ARTERIES.— COELIAC ARTERY. 

R. s. The whole length of the Abdominal Aorta. It is seen embraced by 
the diaphragm at r., and immediately giving off the phrenic and coeliac 
arteries. 

1. The Right Phrenic Artery. 

2. The Left Phrenic Artery. 

3. The Root of the Coeliac Artery. 

4. 4. The Upper Mesenteric Artery. 

5. 5. The Emulgent Arteries. 

6. The Lower Mesenteric Artery. 

7. The Hemorrhoidal Artery, a branch of the last. 

8. 8. The Common Iliac Arteries. 

9. The Internal Iliac. It is seen to give off the gluteal, the ischiatic, and 
the obturator artery. 

The Phrenic Arteries 

Are ramified on the concave surface of the diaphragm, and 
are almost always two in number ; they are denominated right 
and left from their position. They commonly originate sepa- 
rately from the aorta, but sometimes they arise in a common 
trunk which soon divides. In some instances they are derived 
from the coeliac. In a few cases, the aorta furnishes one, and 
the coeliac the other. Each of the phrenic arteries commonly 
crosses the cms of the diaphragm on its respective side, and 
proceeding laterally, in a circular direction, often ramifies so as 
to form an internal and external branch. Each of them gene- 
rally sends branches to the cardia or oesophagus, to the glandular 
renales, and other contiguous parts. 

The Coeliac Artery, 

Is the first great branch given off by the aorta in the abdomen, 
and is distributed almost entirely to the stomach, the liver and 
the spleen. It projects from the anterior part of the aorta so as 
to form a right angle with it, and is of course nearly horizontal, 
when the body is erect. 

The main trunk of this great artery is so remarkably short, 
that it has been compared to the stump of a tree ; for, at the 
distance of half an inch from its origin, it generally divides into 
three branches, which pass to the stomach, the liver, and the 
spleen, and are, therefore, denominated the Gastric or Coronary, 
the hepatic and the splenic arteries. 



GASTRIC OR CORONARY ARTERY. 259 

The first mentioned branch may be called 

The Superior Coronary or Gastric Artery, 

To distinguish it from other branches, soon to be described. 
It is commonly in the centre of the three great ramifications of 
the coeliac, and is also the smallest of them. It proceeds from 
its origin to the upper orifice of the stomach or cardia, and con- 
tinues thence along the lesser curvature of that viscus until it 
approaches near to the pylorus. In ihis course it sends branches 
to the oesophagus, which frequently inosculate with the oesopha- 
geal arteries. It also furnishes branches to the cardia, which 
partially surround it; and, on this account, the artery has been 
called Coronary. Some of these last mentioned branches are 
often continued on the great extremity of the stomach, and an- 
astomose with those ramifications of the splenic artery, called 
Vasa Brevia. 

It continues on the lesser curvature between the lamina of the 
small omentum, and sends off successively branches which pass 
between the peritoneal and muscular coats, and are distributed 
to the anterior and posterior surfaces of the stomach, communi- 
cating with the branches of the inferior gastric arteries, soon to 
be described.* 

The Hepatic Artery 

Proceeds from the great ramification of the cceliac to the 
transverse fissure of the liver called the Porta, in which it ge- 
nerally divides into two branches. In this course it very fre- 
quently sends off an artery to the pylorus, which ramifies about 
the small extremity of the stomach, and often inosculates with 
some of the branches of the superior coronary. This branch is 
called the Pylorica, and sometimes it arises from the artery next 
to be mentioned. 

The Gastrica Inferior Dextra, 
Which also generally originates from the main trunk of the 

* This artery sometimes sends a branch to the liver. When this is the case, it 
is always very large. 



•260 THE SPLENIC ARTERY. 

hepatic, but sometimes from one of its branches. It is an artery 
of considerable size, which proceeds along the great curvature 
of the stomach, from the pylorus towards the great extremity 
between the lamina of the anterior portion of the omentum, and 
distributes its ramifications to both sides of the stomach, and also 
to the Omentum. In its progress from the hepatic artery to the 
stomach, it sends off branches to the Duodenum and to the right 
end of the Pancreas. 

The two great branches into which the hepatic artery divides, 
are denominated right and left, from the lobes of the viscus to 
which they are respectively appropriated. The right branch is 
the largest. Before it penetrates the substance of the liver, it 
sends off a branch to the gall-bladder, called the Cystic Artery. 

The branches of the hepatic artery ramify very minutely in 
the liver, as has been stated in the account of that organ. 

The last great branch of the cceliac is 

The Splenic Artery, 

Which is generally supposed to be larger than the hepatic in 
adults, although it is less in children. It proceeds in a transverse 
direction from its origin to the spleen : its course is not straight, 
but meandering or serpentine. It is situated behind and above the 
pancreas, and passes along the groove in the upper edge of that 
viscus. In its progress, it sends off many small branches, and 
one that is of considerable size, to the Pancreas. It also sends 
one branch to the left extremity of the stomach, which arises 
commonly from the main trunk, but sometimes from the ramifi- 
cations, which are soon to be mentioned. This branch, which 
is called 

The Gastrica Inferior Sinistra, 

Is sometimes, but not often very large : its course is from left 
to right. It is situated between the lamina of the anterior por- 
tion of the omentum. It sends some small branches to the 
omentum, and others which are larger and more numerous, to 
both sides of the stomach. Some of these last mentioned anas- 



SUPERIOR MESENTERIC ARTERY. 261 

tomose with the ramifications of the gastrica dextra which come 
from the hepatic. 

When the Splenic artery approaches near to the spleen, it 
divides into four, five, or six branches, each of which penetrates 
into that viscus by a distinct foramen, and then ramifies in the 
manner described in the account of the structure of the spleen.* 

Either from the splenic artery, or from these ramifications, 
four or five branches pass to the large extremity of the stomach 
and ramify there, communicating with the vessels already de- 
scribed. These arteries have received great attention from 
physiologists, and are denominated Vasa Brevia. 

The Superior Mesenteric, 

Which is the second great branch given off in the abdomen 
by the aorta, is not very different in size from the cceliac, and 
originates about half an inch below it. It is distributed to the 
small intestines ; so that portion of the great intestine which is 
situated on the right side of the abdomen ; and to the arch of the 
colon. From its origin it proceeds downwards, under the pan- 
creas, and over the lower portion of the duodenum, to the com- 
mencement of the mesentery. When it has arrived between the 
lamina of that membrane, it descends in a direction which 
corresponds with that of the root of the mesentery ,+ and forms 
a gentle curve, with its convexity directed towards the intestines. 
It necessarily diminishes as it descends, and generally terminates 
by anastomosing with one of its own branches. This great 
artery sends off some very small ramifications to the pancreas 
and the duodenum, while it is in their vicinity. It also sends two 
or three branches to the transverse part of the colon, to the right 
portion of the colon, to the beginning of the great intestine, and 
the contiguous portion of the ileon. These branches are com- 
monly termed the Colica Media, Colica Dextra, and lleo Colica. 
From the convex side of the curve, the superior mesenteric sends 
off the important branches which pass between the lamina of the 

* It frequently happens that the splenic artery divides only into two or three 
branches, and they subdivide so as to form five or six, which penetrate the spleen, 
t Vol. ii. p. 50. 



2(32 INFERIOR MESENTERIC ARTERY. 

mesentery, and supply the Small Intestines. These branches are 
numerous, and many of their ramifications anastomose with each 
other, so as to form arches. From these arches go off' other 
branches, which anastomose again with some of similar origin; 
and this process is repeated successively several times, so that a 
net-work of blood-vessels seems to be formed on the mesentery. 
From the mesentery the small ramifications are continued, in 
great numbers, to the intestines. Some of them anastomose with 
each other on the coats of the intestine; but an immense number 
of minute arteries are continued 10 the villous coat, so that, when 
they are successfully injected, the surface of that coat appears 
uniformly coloured by the injection.* 

The Inferior Mesenteric Artery 

Does not go off from the aorta next in order after the superior 
mesenteric, but succeeds it immediately on the intestines, and 
continues the arterial ramifications to the left portion of the colon, 
to which the branches of the superior me enteric do not extend. 

This artery arises between the origin of the emulgents and 
the great bifurcation of the aorta, and proceeds downwards, in- 
clining to the left, but keeping near to the aorta. There are 
generally three branches distributed to the left portion of the 
colon, which arise from this artery, either separately, or by a 
common trunk which soon divides. It frequently happens, that 
one of these arteries arises separately, and two by a common 
trunk. These are called the Left Colic arteries ; and are also 
sometimes denominated, from their position, Superior, Middle, and 
Inferior. The Superior generally anastomoses with that branch 
of the superior mesenteric, which is called Colica Media, and 
forms a remarkable arch, called the Great Mesocolic Arch. The 
ramifications of the other branches frequently anastomose with 
each other, and are finally spent upon the left portion of the 
colon. 

The main trunk, diminished by sending off these branches, 

» See the account of the termination of these arteries, at page 44 of this 
volume. 



EMULGENT, CAPSULAR, AND ADIPOSE ARTERIES. 263 

but still of considerable size, runs downwards on the posterior 
part of the intestine rectum, between that intestine and the sacrum, 
where it often divides into two branches, which continue near to 
the termination of the rectum. From them proceed many rami- 
fications that are spent upon the rectum. Some of these rami- 
fications anastomose with each other, and others with the rami- 
fications of the haemorrhoidal artery, soon to be mentioned. 

The Emulgent or Renal Arteries 

Are the large vessels which pass from the aorta to the kidneys. 
They arise between the superior and inferior mesenteries, one 
on each side; and proceed in a direction which is nearly rectan- 
gular to the aorta. The right emulgent artery is necessarily 
longer than the left, and it generally passes behind the vena cava. 
When they approach near the concave edges of the kidneys, 
each emulgent commonly divides into three or four branches, 
which pass into the fissure of that organ, and ramify in the man- 
ner described in the account of it. Sometimes two arteries pro- 
ceed from the aorta to the kidney ; but this is not a frequent oc- 
currence. 

The Capsular Arteries 

Are the small vessels which pass to the glandular renales. 
There are almost always several of them appropriated to each 
gland. They often arise on each side from the cceliac artery, 
the aorta, and the emulgent. 

The Adipose Arteries 

Supply the adipose substance surrounding the kidneys. There 
are several of them on each side, and, like the last mentioned 
arteries, they are very small, and arise from several sources as 
well as the aorta. 

The testicles and ovaria are supplied by the 

Spermatic Arteries, 

Which are very remarkable for their great length and small 
diameter. In a majority of cases, these vessels arise from the 



264 SPERMATIC ARTERIES. 

anterior surface of the aorta, a little below the emulgents : but it 
often happens that the left spermatic arises from the emulgent on 
that side. They also sometimes arise from other neighbouring 
arteries. It has been observed, when they arise from the aorta, 
that the origin of one of them is generally higher than that of the 
other. 

They pass downwards, so as to form an acute angle with the 
aorta, and proceed behind the peritoneum, and before the psoas 
muscle and ureter. While this artery is in contact with the 
psoas muscle, it meets with the ramifications of the spermatic 
vein, and, in its progress to the abdominal ring, also joins the 
spermatic cord. In this course it sends off some very small 
twigs to the contiguous parts, and others that anastomose with 
similar ramifications from the mesenteric, epigastric, &c. Be- 
fore it arrives at the testicle, it divides into several branches, 
two of which generally go to the epididymis, and the others pene- 
trate the upper and back part of the tunica albuginea. 

The Spermatic Arteries in the Female, 

Instead of passing to the abdominal ring, proceed between 
the lamina of the broad ligaments, and send branches to the 
ovaria, which, in some cases, may be traced to the vesicles. 
They also send branches to the Fallopian tubes and uterus, and 
to the round ligaments. Those which are on the opposite sides 
of the uterus, anastomose with each other, and with the branches 
of the hypogastric arteries. 

The lumbar regions are supplied with arteries which originate, 
like the intercostals, from the posterior part of the aorta between 
the thorax and pelvis. There are four or five of these vessels 
on each side, and they are denominated 

The Lumbar Arteries. 

They pass between the spine and the psoas muscle, and send 
branches to the spinal cavity, to the muscles of the lumbar re- 
gions, and the abdominal muscles. They anastomose with the 
internal mammary, the epigastric, the circumflex of the ilium, 

&c. 



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ARTERIES OF THE PELVIS AND HAM. 265 

A small artery passes off singly from the posterior part of the 
aorta at its bifurcation, which is called 

The Middle Sacral Artery. 

It proceeds down the middle of the sacrum to the os coccy- 
gis, and sends off lateral branches, which are spent upon the 
contiguous parts, and inosculate with the arterise sacrae laterales. 

Of the Arteries which originate at and below the Great Bifurca- 
tion of the Aorta. 

The Primitive Macs 

Form an acute angle with each other. They proceed down- 
wards behind the peritoneum, very near the margin of the pel- 
vis, without sending off any branch of importance. At the junc- 
tion of the sacrum with the ossa ilia, they divide into two great 
branches : the Internal Iliac, or Hypogastric, which descends into 
the pelvis ; and the External Iliac, which passes under the crural 
arch to the lower extremity. 

Arteries of the Pelvis and Ham, (from Bell.) See plate facing 

page 265. 

a. The body of the last Lumbar Vertebra sawn through. 
B. The Sacrum. 

c. Ischiatic Ligaments. 

d. The Lumbar Muscles. 

e. The Great Gluteus Muscle. 

f. The Lesser Gluteus Muscle. 

g. The Gracilis Muscle. 

h. The Vastus Externus Muscle. 

i. The Outer Hamstring Muscle ; i. e. the Biceps. 

k. The Inner Hamstring Muscles, i. e. the Semi-tendinosus and Semi-mem- 

branosus. 
l. l. The Triceps. 

M. The Outer Condyle of the thigh bone. 
n. The Liner Condyle. 
o. The Belly of the Gastrocnemius Muscle. 
i>. The Soleus Muscle. 
q. The Achilles Tendon. 
r. The Tibia. 

vol. ii. 23 



266 GENERAL ACCOUNT OF THE INTERNAL ILIAC. 

s. The Flexor Longus Pollicis. 

t. The Flexor Digitorum Communis. 

1. The Internal Iliac Artery ; giving off, 

2. Hypogastric Artery. 

3. 3. Ischiatic Artery. 

4. 4. The Pudic Artery. 

5. The Obturator Artery. 

6. 6. The Gluteal Artery. 

7. A branch from the Internal Circumflex Artery. 

8. Branches of the Perforating Arteries of the Profunda. 

9. The Popliteal Artery after it has pierced the Triceps Muscle. 

10. Those branches sent off from the main artery as it is passing the tendon; 
they are called the perforating branches of the Popliteal Artery. 

11. The Upper and Internal Articular Artery. 

12. The Upper External Articular Artery. 

13. The Lower External Articular Artery. 

14. The Lower Internal Articular Artery. 

15. The Posterior Tibial Artery; the Anterior Tibial Artery (see plate, 
page 265,) is a branch sent off from this. 

16. The Peroneal Artery, or Fibular Artery. 

17. The Posterior Tibial Artery appears here again from under the Soleus 
Muscle. 

18. The Fibular Artery ; it is seen to form large inosculations with the 
Tibial Artery. 

19. A remarkable inosculation betwixt the Tibial and Fibular Arteries. 

20. The External Plantar Artery. 

21. The Internal Plantar Artery. 

The Internal Iliac, or Hypogastric, 

Is distributed, in part, to the viscera of the pelvis and the or- 
gans of generation, and also to the large muscles exterior to the 
pelvis: it is, therefore, very large, although not quite equal to 
the External Iliac. 

It has already been mentioned, that in the foetal state, this 
vessel appears to continue in a curved direction from its origin 
to the lower part of the side of the bladder, and from thence to 
the umbilicus, under the denomination of the Umbilical Artery. 
From the convex side of this curve the different branches of the 
internal iliac go off. In the fostal state they are very small, in 
proportion to the umbilical artery ; but as the artery becomes 
ligamentous, these branches increase in size. 



SMALLER BRANCHES OF THE INTERNAL ILIAC. 267 

In the adult, the arrangement of these vessels is very different. 
The Internal Iliac generally divides into two great branches ; 
the Gluteal, which passes through the sacro-sciatic notch, and 
ramifies on the exterior and upper part of the os ilium : and the 
Ischiatic, which passes downwards on the outside of the tube- 
rosity of the ischium. 

The first of these large ramifications passes out of the pelvis 
above the pyriform muscle, and the last of them below it. Se- 
veral smaller arteries arise from these branches near their origin. 
or from the main trunk of the internal iliac, which are dis- 
tributed to the different parts of the pelvis; and one important 
branch of the ischiatic, called the Pudic, proceeds downwards 
on the inside of the tuberosity of the ischium. 

The first of the smaller branches which the external iliac com- 
monly sends off, is called the 

Ileo Lumbalis. 

It sometimes arises from the gluteal artery, and sometimes 
from the main trunk of the internal iliac. It passes outwards 
under the psoas muscle, and suddenly divides into two branches. 
One of them proceeds upwards, and is distributed in the lumbar 
region, while the other ramifies on the iliacus internus muscle, 
and is spent on the contiguous parts. 

There are, also, two or three small arteries called 

Arteria Sacra: Laterales, 

Which sometimes arise singly, and sometimes in common, 
from the great trunk. They also occasionally originate from 
the gluteal artery. These vessels enter the anterior foramina of 
the os sacrum, to be distributed on the cauda equina and the 
membranes which invest it. Some of their ramifications anas- 
tomose with branches of the sacra media and other contiguous 
arteries. 

On the anterior side of the internal iliac, near the origin of 
the above mentioned vessels, a ligament, which was originally 
the umbilical artery, goes off to the side of the bladder, and con- 
tinues from thence to the umbilicus. Sometimes it continues 



268 SMALLER BRANCHES OF THE INTERNAL ILIAC. 

pervious for a short distance, and then small branches pass from 
it to the bladder. 

In the female it also sends small branches to the uterus and 
vagina. 

In addition to these Vesical Arteries derived from the umbili- 
cals, there are other branches distributed to the bladder, which 
arise very differently, in different subjects, from branches which 
are soon to be described, as the hemorrhoidal, pudic, &c. 

From the anterior side of the internal iliac, or from one of its 
great branches, an artery often arises which passes out of the 
pelvis through the aperture in the margin of the ligamentous 
membrane which closes the foramen thyroideum of the os inno- 
minatum ; this is called the 

Obturator Artery. 

This vessel, while it is in the pelvis, often sends small branches 
to the bladder and its appendages, and to the obturator internus 
muscle. After it passes out of the pelvis, it frequently divides 
into branches; some of which are spent on the obturator exter- 
nus, and the contiguous muscles, and others go to the hip joint. 
The origin of this artery is variable. Most commonly it arises 
from the internal iliac, but often from the ischiatic, and some- 
times from the gluteal. In some instances, it originates in a way 
that is particularly interesting, when the operation for crural 
hernia is to be performed, viz. from the epigastric artery, soon 
to be described : for in this case the obturator artery sometimes 
nearly surrounds the neck of the hernial sac* 

A small artery passes from the internal iliac or one of its 
branches, to the rectum, which is called the 

Middle Hemorrhoidal, 

From its situation between the branches which are sent to that 
intestine from the inferior mesenteric, and those which go to it 

* See Astley Cooper's great work on Hernia, vol. i. 

There is reason to believe that this position of the artery occurs more frequently 
than has been supposed. 



LARGER BRANCHES OF THE INTERNAL ILIAC. 



269 



from the pudic. This artery is spent upon that part of the 
rectum which is above and in contact with the sphincter. It 
sends branches to the prostate and vesiculae seminales, in males, 
and to the vagina and bladder in females. 
In females there is a peculiar artery, 

The Uterine, 

Which originates either from the internal iliac, near the origin 
of the ischiatic, or from one of its branches. It passes between 
the lamina of the broad ligaments to the cervix uteri, and pene- 
trates the texture of that organ. The size of this vessel varies 
with the varying size of the uterus. 

The Gluteal or Posterior Iliac Artery, 

One of the two great branches of the internal iliac, proceeds 
exteriorly through the sciatic notch above the pyriform muscle. 
very near the edge of the bone. On the outside of the ilium it 
generally divides into two branches, one of which ramifies be- 
tween the gluteus medius and minimus, and the other between 
the medius and maximus. It is principally spent upon these mus- 
cles, and sends branches to the contiguous parts. 

The Ischiatic Artery. 

The other great branch of the internal iliac, passes through 
the sciatic notch below the pyriform muscle, and proceeds down- 
wards, between the great trochanter of the os femoris and the 
tuberosity of the ischium, under the gluteus maximus muscle. 
Soon after its origin, it commonly sends off a considerable branch, 
the Arteria Pudica, which also passes downwards: it then con- 
tinues its course as above mentioned, and its principal branches 
are distributed to the gluteus maximus and the muscles of the 
upper and back part of the thigh, while its smaller branches go 
to the os sacrum and coccyx, and the contiguous small muscles. 

The Pudica Interna, 

As has been just mentioned, is often a branch of the ischiatic 
artery, but sometimes originates immediately from the internal 

23* 



270 PUDIC ARTERY.— EXTERNAL ILIAC. 

iliac. It proceeds downwards and inwards, diverging from the 
ischiatic, and passing between the two sacro-sciatic ligaments to 
the interior side of the tuberosity of the ischium, whence it con- 
tinues on the inside of the crus of the os ischium and pubis until 
it approaches the symphysis, when it generally divides into three 
branches, which are spent upon the organs of generation, from 
which circumstance the name of this artery is derived. 

One or more branches from it also pass to the lower part of 
the rectum and sphincter ani, and are called the Lower Hcemor- 
rhoidal Arteries. 

In its course, it sends off many small branches to the con- 
tiguous parts ; one of which, called the Perineal, leaves it near 
the transversus perinei, and passes between that muscle and the 
skin, and between the bulb of the urethra and the crus of the 
penis, to the scrotum. 

When the Pudic has arrived near the bulb of the urethra, it 
sends a branch into it, which is continued into the corpus spon- 
giosum urethras, and ramifies there minutely. 

At the symphysis of the pubis it sends off a second branch, 
which passes to the back of each crus, and, proceeding along it. 
parallel to its fellow, terminates in the glans penis: in this course 
it sends branches to the elastic coat, to the integuments, and to 
the prepuce. This vessel is called the Arteria Dorsalis. 

The main trunk of the pudic artery then penetrates the corpus 
cavernosum, and proceeds through it in a straight direction. Its 
ramifications appear to be distributed through the internal struc- 
ture of the corpus cavernosum, and some of them extend through 
the septum to the other side, while others pass to the corpus 
spongiosum urethras. 

The External Iliac, 

The great artery of the lower extremity, appears soon after 
birth, like a continuation of the primitive iliac, and proceeds 
along the brim of the pelvis behind the peritoneum, to Poupart's 
ligament, or the crural arch, under which it passes. 

The psoas muscle is at first in contact with it on the outside, 
and the internal iliac vein on the inside. As it passes under 



EPIGASTRIC ARTERY—CIRCUMFLEX ARTERY 271 

Poupart's ligament, it is immediately anterior to the psoas and 
iliacus internus muscles, where they are united, and the crural 
nerve is exterior to it. Before it arrives at the lower edge of 
Poupart's ligament, it sends off 

The Epigastric Artery, 

Which arises on its internal side, and proceeds downwards 
and inwards about half an inch ; then it turns upwards and in- 
wards, and continues in that direction for a small distance, after 
which its course is less oblique. It passes between the peritoneum 
and the abdominal muscles, behind the spermatic cord, and the 
round ligaments in females. 

It generally changes its oblique direction after passing about 
two inches, and then proceeds in contact with the rectus, and 
very near its external edge, its ramifications are expended upon 
the anterior parietes of the abdomen ; and after it has arrived as 
high as the umbilicus, it commonly divides into branches which 
often inosculate with the ramifications of the internal mammary." 

An artery which is rather smaller than the epigastric, arises 
nearly opposite to it, but rather lower, from the external side' of 
the external iliac. It is called 

The Circumflex Artery of the Os Ilium, 

And proceeds upwards and outwards to the upper margin of 
the os ilium, along which it continues very near to the spine. It 
is distributed principally to the abdominal muscles, to the iliacus 
internus and the psoas, and the parts contiguous. 

The artery of the lower extremity, after passing under Pou- 
part's ligament, takes the name of 

Femoral Artery, 

And proceeds downwards in a direction so spiral, that although 
it is in front at the upper part of the thigh, it is completely behind 

* Several respectable surgeons have been taught by experience, that when the 
abdomen is distended by ascites, the position of the epigastric artery is so much 
altered, that it will sometimes be found in the middle of the oblique line, which 
extends from the umbilicus to the superior anterior spine of the ilium. 



272 FEMORAL ARTERY.-PROFUNDA. 

at the lower part. It sends branches to the muscles of the thigh, 
as the aorta does to the viscera of the abdomen, viz. by a few 
large vessels which extend and ramify to a great distance among 
them. 

The situation of the adductor muscles, and their attachment 
to the os femoris, is such, that the artery in this course must 
necessarily perforate their common tendon, which it does at the 
distance of one-third of the length of the bone from its lower 
end. The aperture in this tendon corresponds precisely with the 
general course of the artery ; and before the artery enters this 
perforation, it is on the internal side of the bone ; after it has 
passed the perforation, it is on the posterior side of it. After 
passing through the tendon of the adductors, it is denominated 
The Popliteal Artery, and it retains this name until it divides. 

It then proceeds downwards, being very near the bone, and 
between the tendons of the flexors of the leg, covered by the 
great nerve of the lower extremity, and very often, also, by the 
vein. After crossing the articulation of the knee, when it is be- 
tween the heads of the gastrocnemii muscle, at the lower edge 
of'the popliteus muscle, it divides into the anterior tibial and the 
common trunk of the peroneal and posterior tibial arteries. 

The Femoral artery, soon after emerging from Poupart's liga- 
ment, sends off very small branches to the inguinal glands, and 
other contiguous parts. It also sends off the 

External Pudics, 

Which are two or three small arteries that are generally spent 
upon the scrotum in males, and the Labia Pudendi in females. 

About two inches below Poupart's ligament, the great branch 
which has been called the muscular artery of the thigh, leaves 
it. This vessel is commonly denominated 

Arteria Profunda. 

It arises from the back part of the trunk of the femoral, and 
passes downwards and backwards, in a way that has been com- 
pared to the separation of the internal iliac and the external. 
Very soon after its origin, it sends off two branches, which pro- 



CIRCUMFLEX ARTERIES. 273 

ceed, one on the internal, and the other on the external side of 
the thigh, and are called the circumflexa interna and externa. 
It then passes downwards behind the trunk of the femoral, and 
sometimes very near it, on the adductor muscles, and finally 
divides into branches, which are called the Perforating. 

The External Circumflex 

Sometimes arises from the femoral, but most commonly is a 
branch of the profunda, as above stated. It passes under the 
rectus and tensor vaginas femoris towards the great trochanter, 
and generally divides into two branches, one of which continues 
in the transverse direction, and sends branches to the upper and 
back part of the thigh, and the parts contiguous to the joint ; 
while the other descends in the course of the rectus femoris 
muscle, and some of its ramifications extend near to the outside 
of the knee. 

The Internal Circumflex 

Is often smaller than the other. It generally passes between 
the psoas, and the pectineus muscles, and continues round the 
thigh towards the lesser trochanter. Its ramifications are ex- 
pended on the upper portions of the adductor muscles and the 
muscular parts contiguous to the lesser trochanter. It also sends 
branches to the articulation. 

The Perforating Arteries 

Are two or three ramifications of the profunda, which pass 
through the adductor muscles, and are expended upon the flexor 
muscles on the back of the thigh. Some of the terminating 
branches of the profunda itself are also called perforating ar- 
teries. 

The next branch of importance which is sent off by the Femo- 
ral artery, leaves it before it enters the aperture in the tendon of 
the adductors, and is called 

The Anastomotic Artery. 
This vessel soon inclines downwards. Its ramifications ex- 



274 POPLITEAL ARTERY. 

tend into the vastus internus muscle ; some of them follow the 
tendon of the adductors, and ramify about the internal condyle. 

Several small branches go off from the great artery soon after 
it passes through the tendon of the adductors, which are distri- 
buted to the contiguous muscles. Some of them are also called 

Perforating Arteries. 

Among them is the principal Medullary Artery of the os 
femoris. 
In the ham, the great vessels there called 

Popliteal, 

Generally send off several small branches. Two of them go off 
on the inside, one above and the other below the knee ; and 
two on the outside in the same manner. They are named, from 
their situation, The Superior and Inferior Internal, and The Su- 
perior and Inferior External Articulary Arteries. 

The Superior Internal artery perforates the tendon of the ad- 
ductors above the internal condyle, and ramifies minutely on the 
inner side of the joint. 

The Superior External artery passes through the lower por- 
tion of the biceps above the external condyle, and ramifies 
minutely on the outer side of the joint. Its superior ramifica- 
tions anastomose with those of the descending branch of the 
external circumflex, while its inferior ramifications communicate 
with those of the corresponding artery below. 

The two inferior arteries originate nearly opposite to the mid- 
dle of the joint, and pass downwards. 

The Inferior Internal artery passes under the internal head of 
the gastrocnemius muscle, on the posterior and internal side of 
the head of the tibia. Its ramifications communicate with those 
of the corresponding artery above and of the tibialis antica be- 
low. They also extend to the interior of the joint. 

The Inferior External artery passes under the external head of 
the gastrocnemius and the plantaris muscle, and continues under 
the external lateral and capsular ligament. It is distributed on 
the external and inferior part of the articulation, and sends also 
some branches to the interior of the joint. 



POSTERIOR AND ANTERIOR TIBIAL ARTERIES. £75 

There is frequently an azygous vessel, called the Middle Arti- 
cular artery, which arises from the back of the popliteal, and is 
distributed to the posterior part of the articulation. 

The Popliteal artery, after this, sends off a few small branches 
to the heads of the muscles of the leg, and among them one of 
considerable length, to each of the heads of the gastrocnemii. 
At the under edge of the popliteus muscle, it sends off horizon- 
tally a large branch, which passes directly forward between the 
tibia and the fibula, above the commencement of the interosse- 
ous ligament. After this, it continues to descend, nearly in the 
same direction, under the soleus muscle, behind the tibia; but 
before it has proceeded farther than twelve or fifteen lines, it 
sends off a branch which forms an acute angle with it, and ap- 
proaches near the fibula, along which it descends. 

The branch sent off anteriorly, is called the Anterior Tibial 
artery. 

The main trunk, which continues downwards, is called the 
Posterior Tibial artery ; 

And the branch which descends near the fibula is called the 
Peroneal or Fibular artery. 

The Anterior Tibial Artery, 

After its arrival on the anterior part of the leg, passes down 
close to the interosseous ligament, with the tibialis anticus mus- 
cle on the inside, and the extensor communis on the outside, in 
the first part of its course; and afterwards, with the extensor 
pollicis pedis on the outside of it. It gradually inclines internal- 
ly as it descends, so that a little above the ankle it is upon the 
front part of the tibia. It proceeds thence with the tendons of 
the extensor digitorum pedis, under the annular ligament, to the 
upper surface of the foot, on which it continues to the interstice 
of the first and second metatarsal bones, where it descends to 
anastomose in the way presently to be mentioned. 

In this course it sends off, soon after it has arrived at its ante- 
rior situation, a recurrent branch, which is distributed to the 
heads of the muscles and the ligaments of the articulation, and 
which anastomoses with the branches of the inferior articular 



276 PERONEAL ARTERY. 

arteries. It also sends off, on each side, many arterial twigs to 
the contiguous muscles, and very frequently one branch of con- 
siderable size, which passes down near the fibula. - 

When it has arrived near the end of the tibia, it sends a branch 
on each side, called the Internal and External Malleolar. On 
the top of the foot, among several smaller arteries, it sends off a 
branch under the extensor brevis digitorum pedis, which passes 
outwards and forwards, and supplies the muscles, &c. on the 
upper part of the foot. This vessel is called Arteria Tarsa. 
There is also another branch, called Metaiarsa, which generally 
arises about the middle of the foot, and passes obliquely outward 
and forward, supplying the contiguous parts. 

The Anterior Tibial artery, having arrived at the space be- 
tween the metatarsal bones of the first and second toes, bends 
down to the sole of the foot, but previously sends off a branch 
which passes near the external edge of the metatarsal bone of 
the great toe, and divides into two branches, one of which goes 
to the outside of the great toe, and the other to the opposite side 
of the toe next to it. 

The Posterior Tibial Artery 

After sending off the anterior tibial, parts with the Peroneal or 
Fibular, as has been already stated, and then continues on the 
back of the tibia, behind the internal ankle, to the sole of the foot. 

The Peroneal or Fibular Artery 

Is not commonly so large as either of the two other arteries 
of the leg, nor is it so constant. It passes down very near the 
internal edge of the fibula. It is in contact, for some distance, 
with the tibialis posticus muscle, and is anterior to the soleus and 
the flexor pollicis longus; it sends branches to the contiguous 
muscles. After it has passed along two-thirds of the length of 
the fibula, it frequently, but not always, divides into an anterior 
and a posterior branch. 

The anterior peroneal soon perforates the interosseus ligament, 
and passing down some distance on its anterior surface, continues 
to the ankle and upper surface of the foot. It gives ramifications 



INTERNAL PLANTAR ARTERY. 277 

to all the contiguous parts in its progress, and anastomoses with 
some of the small ramifications of the tibialis antica. 

The posterior peroneal branch is the continuation of the main 
trunk. It passes behind the external malleolus, and ramifies 
upon the external side of the foot. 

The posterior tibial artery passes down, inclining rather ob- 
liquely inwards, between the gastrocnemius internus, which is 
posterior to it, and the tibialis posticus and flexor digitorum, 
which are anterior to it. Upon the leg it gives off many small 
branches, one of which, termed the Arteria JVutritia Tibia, comes 
oft' high up,* and, after ramifying as it descends, sends a branch 
to the medullary foramen of the tibia. 

At the lower part of the leg, the Posterior Tibial is situated 
rather superficially between the tendo Achillis and the tibia. It 
proceeds thence behind the internal ankle in a deep situation, 
covered by an annular ligament, and passes between the abductor 
muscle of the great toe and the bones of the tarsus. It then 
divides into two branches— the internal and the external plantar 
arteries. 

The Internal Plantar Artery 

Is commonly much smaller than the other ramification. It 
passes in the direction of the internal edge of the foot, but at 
some distance from it. and often lies between the aponeurosis 
plantaris and the abductor pollicis. It frequently terminates by 
anastomosing with one of the arteries of the great toe, and in its 
course sends off several branches to the contiguous parts on each 
side of it. 

The External Plantar Artery 

Is the continuation of the main trunk. It proceeds outwards 
and forwards between the short flexor of the toes and the flexor 
accessorius ; and continues afterwards between the first of these 
muscles and the abductor of the little toe. At the metatarsal 
bone of the litttle toe it begins to curve, and continues its curva- 

* This artery sometimes comes off from the popliteal. 
VOL. II. 24 



278 EXTERNAL PLANTAR ARTERY. 

ture across the other metatarsal bones to the interstice between 
the great toe and the one next to it, passing between the tendons 
of the long extensor and the metatarsal bones. At the interstice 
above mentioned, it anastomoses with the tibialis amicus. The 
curvature, thus formed, is called the Arcus Plantaris. 

In this course, the External Plantar sends off several branches 
to the heel and the parts of the foot, especially on the external 
side ; the deep-seated parts of the foot being supplied from the 
curve. 

Digital branches go off from the curve, as they do in the hand, 
from the curve of the ulnar. There is first a small branch to 
the outside of the little toe, and then three regular branches, 
which pass to the junction of the roots of the four small toes, and 
divide, like the digital arteries of the hand, so as to send a branch 
to the side of each toe. These digital arteries pass between the 
muscle called Transversalis Pedis and the metatarsal bones. 
Near the heads of these bones, each of them generally sends off 
two arteries that pass upwards between the interossei muscles and 
the bones, and anastomose with the ramifications from the top of 
the foot. 

The External Plantar, soon after sending off the third digital 
artery, anastomoses with the anterior tibial, and then continues 
to the junction of the root of the great toe with the one next to 
it, when it divides into two branches, which go to the opposite 
sides of those toes. In its course it also sends a branch to the 
internal side of the great toe. 

Of the Arteries of the Lower Extremity. (See Plate facing p. 279.) 

a. The Tendon of the External Oblique Muscle. 

b. The Sartorius Muscle. 

c. The Gracilis. 

d. The Triceps Muscle. 

e. The Rectus Femoris. 

f. The Vastus Internus. 

g. The Vastus Externus. 
h. The Patella. 

i. The Tibia. 

k. The Head of the Fibida. 
















y/- 




|: : 



I* 



-: §f ' 






JV 



"a 



cti 



/ : /,:,/ ,/, 



,-i. 






ARTERIES OF THE LOWER EXTREMITY. gijg 

h. The Gastrocnemius Muscle. 

m. The Solcus Muscle. 

n. The Tibialis Anticus. 

o. The Extensor Tendons of the Toes. 

Arteries. 

1. The Femoral Artery. 

2. The Epigastric Artery. 

3. The Circumflexa Hit. 

4. A Cutaneous Branch to the head of the Sartorius, and glands, and fat. 

5. To the Inguinal Glands, and Fat ; it sends out a pudic branch also. 

6. The External Pudic Artery. 

7. The Profunda. 

8. The Internal Circumflex Artery. 

9. The Profunda, proceeding deep into the flesh of the thigh before it 
• gives off* the perforating branches. 

The Branches of the Profunda are seen in the interstices of the Rectus and 
Vastus Externus. 

10. The Femoral Artery, where it lies betwixt the triceps and vastus inter- 
ims muscle, before it perforates the triceps.* 

ll,t 12, 13. Articular Arteries, branches of the Popliteal Artery. 

14. The Anterior Tibial Artery. \ 

* Femoral Artery. This artery, near the place of its perforating the triceps, is 
the subject of one of the most important surgical operations for popliteal aneurism. 
In dissection it may be well to make this experiment: Place a string so as to reach 
from the superior spine of the os ilii to the prominent part of the inner condyle ; 
mark the middle of the string ; make an incision a very little towards the inside of 
it, in the direction of the string ; first, you come to the sartorius muscle ; next, 
laying that aside, to a fascia, which stretches from the triceps to the vastus inter- 
nus; when this is slit up you may see the artery ; observe its situation in regard 
to the vein, the nervus longus, and the sheath which surrounds it. 

t This branch (the first perforating branch of the Popliteal Artery) is remarka- 
bly enlarged in Popliteal Aneurism. 

t The Anterior Tibial Artery lies so under the projection of the Tibia, that it is 
not ofien wounded ; yet it may be cut by a deep wound, and the student should 
observe how it lies under the fascia and muscles. 

"The Anterior Tibial Artery comes through betwixt the bones, one inch below 
the projection of the knob of the Fibula ; we then cut by the edge of the Peronevs 
Longus, and follow the partition fascia, which is betwixt this muscle and the head 
of the Extensor Digitorum Communis. This partition carries us deep, and we 
find the artery lying on the interosseous ligament." 

When the artery is to be tied lower down, after slitting up the fascia, we must 
cut betwixt the Tibialis Anticus, and Extensor Pollicis. 



280 ARTERIES OF THE LOWER EXTREMITY 

15. The Reflected Branch of the Anterior Tibial Artery. 

16. The Anterior Tibial Artery, continuing its course, and distributing 
small branches to the surrounding muscles. 

17. At this part it passes under the Annular Ligament. 

18. The Internal Malleolar Artery. 

19. The External Malleolar Artery. 

20. The Tarsal Artery. 

21. The Anterior Tibial Artery descending on the fore part of the foot. 

22. The part at which the Anterior Tibial Artery sinks into the sole of the 
foot, forming communications with the Plantar Arteries. 

23. The last branch of the Anterior Tibial Artery, the Arteria Dorsalis 
Pollicis. 



DISTRIBUTION OF THE VEINS. 281 



CHAPTER IX. 

OF THE PARTICULAR DISTRIBUTION OF THE VEINS. 

Anatomists of great respectability have very different senti- 
ments respecting the best method of describing the veins. Some 
of them, in order to follow the course of the circulation, com- 
mence with the small veins, and proceed to the large trunks 
which are formed by their union. Others begin with the great 
veins that empty into the heart, and proceed from them to the 
small ramifications of the venous system, in a direction the re- 
verse of the circulation. 

As the last method is the easiest, for the student of anatomy, it 
will be adopted here; but it must always be kept in mind, that 
the blood flows from the small veins into the larger, and not from 
the latter into the former, as the mode of description seems to 
imply. 

The great trunk of the venous system differs considerably 
from that of the arterial with respect to its connexion with the 
heart; for it communicates with that organ in such a manner, 
that, when viewed from before, it appears like two vessels ; one 
opening into the upper, and the other into the lower part of the 
right auricle. When viewed from behind, it appears like a 
continued tube, three-fourths of which are deficient anteriorly ; 
and to the margin of this deficiency the right sinus or pouch of 
the heart is connected. 

In some preparations of the heart, where all the great vessels 
connected with it are much distended by the injection, and the 
pulmonary vessels are injected first, the right auricle is so much 
pressed upon from behind, by the vessels which go to the right 
lung, that the direction of the superior and inferior portions of 
the vena cava, which thus communicate with it, is altered. Each 

24* 



282 COROXARV VEINS OF THE HEART. 

/ 

of them is turned obliquely forwards, so that it forms an angle 
with the other. This occasions them to appear more like distinct 
vessels than they otherwise would do. 

The above mentioned portions of the great veins are denomi- 
nated the Superior or Descending, and the Inferior or Ascending 
Vena Cava; as if they were perfectly distinct and unconnected 
with each other. 

The Coronary Veins, 

Which are exclusively appropriated to the heart, may be con- 
sidered here, as they are not included in the general arrangement 
of the veins. 

The great vein of the heart begins at the lower part of the 
right auricle, very near to the septum, which divides the two 
auricles. It soon proceeds to the left in a circular direction, 
surrounded with adipose matter, in the deep groove which exists 
between the left auricle and the left ventricle. It continues be- 
tween trie auricle and ventricle, until it is immediately over the 
septum, which divides the two ventricles. Here its direction 
changes, and it proceeds to the apex of the heart, where its small 
ramifications anastomose with others soon to be described. In 
its course round the basis of the left ventricle, it sends off several 
branches, one of which is considerable, that proceed from the 
basis towards the apex of the heart, ramifying on the surface of 
the left ventricle. 

A second vein, much less than the first, appears to proceed 
from the great vessel at its commencement,* and continues on 
the lower flat surface of the heart, between the two ventricles, 
to the apex, accompanied by a branch of the right coronary 
artery. This has been called the Middle Vein of the heart. 

In addition to these there are several veins which begin at the 
right auricle, and extend on the surface of the right ventricle to- 
wards the apex of the heart. These have been called the Ante- 
rior Veins. 

* It often opens into the auricle by a separate orifice. 



SUPERIOR VENA CAVA AND ITS GREAT BRANCHES. 



283 



Of the Superior or descending Vena Cava, and the veins which 
communicate ivith it. 

This great vessel proceeds upwards from the superior and pos- 
terior part of the right sinus or pouch of the heart ;* and a por- 
tion of it is so involved by the pericardium, that it seems to be 
included in that sac, as the heart is in this situation. It is some- 
what anterior as well as to the right of the aorta. It con- 
tinues above the pericardium, adhering to the right lamen of the 
mediastinum, and rather inclining forward. When it is as high 
as the lower margin of the upper rib, it sends off a very large 
branch, which conveys the venous blood of the left arm and 
the left side of the head and neck. This large vein, which is 
very important, both on account of its size and situation, pro- 
ceeds in a transverse direction within the sternum, almost in con- 
tact with, and but little below, the upper and internal margin of 
that bone. Immediately behind, or within the origin of the left 
sterno-mastoid muscle, it divides into the left subclavian, which 
preserves a transverse course, and the left internal jugular, which 
proceeds to the cavity of the cranium by the foramen lacerum. 

After sending off this transverse branch to the left, the great 
vein continues upwards and behind the right sterno-mastoid mus- 
cles, and there sends off, nearly at right angles, the right subcla- 
vian vein. After it has parted with this vein, it takes the name 
of Internal Jugular, and continues to the right foramen lacerum, 
in the basis of the cranium. The superior vena cava is, there- 
fore, principally formed by the union of the subclavians and in- 
ternal jugulars from each side of the body. 

Immediately after the superior cava rises above the pericar- 
dium, before it divides as above stated, it sends off, from its pos- 
terior part, a large vein which is single, and, therefore, called 

Vena Azygos. 

This vessel projects backwards above the right pulmonary 
artery and right branch of the trachea, and then curves down- 

* See description of the heart, vol. i. page 450. 



OQ4 VENA AZYGOS. 

wards behind them. It proceeds down the spine to the right of 
the aorta and at a small distance from it, into the abdomen, be- 
tween the crura of the diaphragm, and sometimes between some 
of the portions of that muscle, which are attached to the dorsal 
vertebrae. In the abdomen it often anastomoses either with the 
lumbar veins or the vena cava. 

The azygos frequently sends off several small veins from its 
curvature to the contiguous parts, and also the right Bronchial 
Vein, which passes along the ramifications of the trachea into 
the substance of the lungs.* In its course downwards it gives 
off branches to the oesophagus, some of which are consider- 
able. 

The Inferior Intercostal Veins originate directly or indirectly 
from the azygos. In some cases there is no superior intercostal 
on the right side ; and then the two or three uppermost of the 
right intercostals are also derived from the azygos ; and often 
originate from it by a common trunk, which soon divides. Most 
commonly the ten inferior intercostals on the right side proceed 
directly from the azygos, and accompany the intercostal arteries. 
Their posterior branches pass into the vertebral cavity, and com- 
municate with the veins which are there. 

About the sixth or seventh rib, the vena azygos frequently sends 
off a branch to the left, which descends on the left side of the 
vertebrae, and sends off those left intercostal veins which are 
below its origin. It passes through the diaphragm with the aorta, 
or to the left of it, and anastomoses either with the azygos itself, 
or in a way which is analogous to the anastomosis of that 
vessel. 

The Vena Azygos may be regarded as the great trunk of the 
veins of the parietes of the thorax, which are thus collected, be- 
cause they could not with convenience pass singly to the vena 
cava, as the arteries do to the aorta. 

Soon after sending off the vena azygos, the Superior Cava 
sends off the great transverse branch above mentioned. From 
this it continues upwards but a short distance, when it divides, 

* This bronchial vein sometimes arises from the superior cava. 



SUPERIOR INTERCOSTAL VEINS. 285 

behind the right sterno-mastoid muscle, into the right subclavian 
and right internal jugular. 

The branches of the superior cava, which thus intervene be- 
tween the great trunk and the subdivisions behind the sterno-mas- 
toid muscles, are often called the Subclavian Veins; but they do 
not appear to be accurately named. For, 1st, they are not situ- 
ated under the clavicle, and, 2dly, they are the common trunks 
of the subclavians and internal jugulars united. 

There is a difference in the places where some of the smaller 
veins originate on each side. The internal mammary and the 
inferior thyroid, on the right side, arise from the superior cava, 
or from the subclavian at its origin. On the left side, they arise 
from the subclavian. 

The Superior Intercostal Veins 

Are somewhat different on the two sides. That on the right 
is often the smallest and the least extensive. It commonly ori- 
ginates from the posterior and inferior part of the subclavian 
opposite to the origin of the vertebral, and is generally distri- 
buted to the first and second intercostal spaces, but rarely to the 
third. 

The Left Intercostal frequently originates near the left internal 
mammary, and sometimes in common with it. It descends be- 
hind the aorta on the left of the spine, and commonly sends off 
the six upper intercostal veins, of which the two or three supe- 
rior pass upwards from a part of the vein which is opposite to 
the third dorsal vertebra. Its extent is very different in different 
subjects. In some instances it passes so low as to supply the 
seventh or eighth intercostal space. This vein also gives off the 
Left Bronchial Vein, which sends branches to the oesophagus 
and bronchial glands. 

The Vertebral Veins 

Arise from the subclavians, but sometimes they proceed diffe- 
rently in different subjects : the right passing behind, and the left 
before the subclavian artery of its respective side. Each of 
them, however, becomes contiguous to its corresponding artery. 



280 VERTEBRAL VEINS. 

When it has arrived at the place in the transverse processes, 
where the artery enters the vertebral canal, it sends off an ex- 
ternal branch, which passes up before, and nearly in contact 
with those processes, and gives ramifications to the contiguous 
muscles, and also to the cavity of the spine. These last men- 
tioned ramifications enter by the lateral apertures between the 
transverse processes, and anastomose with the veins and sinuses 
of the cavity. The branch often finally terminates in the lateral 
sinus of the dura mater, by passing through the foramen near 
the mastoid process of the temporal bone. The Main Trunk of 
the vertebral vein generally sends offanother external branch to 
the muscles near the basis of the neck, and afterwards enters the 
canal with the vertebral artery. While in this canal, it generally 
sends off two branches through each of the lateral apertures be- 
tween the vertebras. One of these branches passes backwards 
to the muscles of the neck, and the other proceeds into the great 
spinal cavity, and communicates with the venous sinuses. 

When it has arrived at the atlas, the Vertebral vein sends 
branches to the contiguous muscles of the neck. It also fre- 
quently sends a branch through the posterior condyloid foramen 
of the occipital bone to the lateral sinus. 

Jt is evident, from these circumstances, that the vertebral vein 
carries a portion of blood from the sinuses of the brain and of the 
spinal marrow, as well as from the muscles of the neck, into the 
subclavian veins. 

The veins of the head are frequently very different in different 
subjects. 

The Internal Jugular, 

Already mentioned, is often almost exclusively appropriated 
to the cavity of the cranium ; and all the exterior veins of the 
head are ramifications of one or more smaller vessels, which 
pass up superficially on the neck, and are denominated External 
Jugulars. In some instances almost all the exterior veins of the 
head are united to the internal jugular at the upper part of the 
neck, and it of course conveys the blood of the exterior as well 
as of the interior parts of the head. Frequently these veins are 



THE INTERNAL JUGULAR. 287 

divided between the internal and external jugulars, but they are 
divided very differently in different subjects. 

The Internal Jugular, however, almost always passes in the 
same direction from the inside of the origin of the sterno-mastoid 
muscle to the posterior foramen lacerum of the cranium. It is 
deeply seated on the external side of the common carotid artery, 
and under the sterno-mastoid muscle. Between the upper mar- 
gin of the thyroid cartilage and the angle of the lower jaw, it 
often sends off branches which are very different in different 
subjects, but commonly pass to the anterior parts of the neck and 
face: above these it generally sends another to communicate 
with the external jugular. One of the branches which often go 
off from the internal jugular is that which corresponds with the 
superior thyroid or laryngeal artery. This vein, which has 
sometimes been called the Guttural, sends many ramifications to 
the thyroid gland. The Ranular veins, which are so conspicu- 
ous under the tongue, are also derived from it; and it likewise 
sends branches to the larynx and pharynx. 

Before the internal jugular enters the foramen lacerum, it 
suffers a partial dilatation, which is generally larger on one side 
than the other.* This dilatation occupies the fossa at the fora- 
men lacerum. After passing through the aforesaid foramen, the 
internal jugular terminates in the lateral sinuses of the dura 
mater.f These and the other sinuses within the cavity of the 
cranium are important portions of the venous system, which are 
interposed between the smaller branches spread upon the pia 
mater and the great trunks of the neck. They will be de- 
scribed in the account of the brain. Into these sinuses the 
very numerous veins of the pia mater open, proceeding to the 

* When the veins of the neck are injected, it very often appears that a conside- 
rahle portion of the internal jugular is much larger on one side than the other, as 
if it were affected with varicose distention. 

It also often appears that the general arrangement of the exterior vein is differ- 
ent on the two sides of the head and neck. 

t It is asserted that the internal coat, or lining membrane of the internal jugu- 
lars, is continued into the lateral sinuses, and extends throughout all the sinuses of 
the dura mater ; so that the blood, during its passage through the sinuses, does not 
come in contact with any membrane different from that of the veins. 



288 THE EXTERNAL JUGULAR. 

sinuses in a direction the reverse of that in which the blood flows 
in those channels. 

These veins are divided very minutely on the pia mater before 
they enter the substance of the brain. 

Into one of these sinuses, denominated the Cavernous, the oph- 
thalmic vein discharges its contents. This vein proceeds from 
the anterior part of the sinus into the orbit of the eye through 
the sphenoid fissure.* Its ramifications correspond generally 
with those of the ophthalmic artery ,f and some of them pass out 
of the orbit to anastomose with the branches of the facial vein. 

The superficial veins of the neck are variously arranged in 
different persons. There is often one considerable vein, 

The External Jugular, 

Which is sent off by the subclavian, very near its union with 
the internal jugular ; but sometimes it goes off from that vein 
much nearer the shoulder. There are sometimes two external 
jugulars, an anterior and posterior, nearly of equal size. More 
frequently one of them is much smaller than the other. In a 
majority of cases, the principal external jugular goes off near the 
junction of the internal jugular and subclavian, as above stated, 
and proceeds upwards towards the angle of the lower jaw, pass- 
ing between the platysma myoides and the sterno-mastoid mus- 
cle. It often sends off, at the basis of the neck, one or 
more branches to the contiguous muscles, and then proceeds up- 
wards. Near the angle of the jaw, it often communicates with 
the internal jugular : it then continues upwards, covered with 
the parotid gland, near the temporal artery, and finally divides 
into superficial and deep-seated temporal branches. 

The External Jugular, near the angle of the jaw, often sends 
off the facial vein, which crosses the basis of the lower jaw, near 
the facial artery, and distributes branches to the side of the face 
and to the forehead. It also very often sends off, near this place, 
the internal maxillary vein, which generally ramifies in such a 

* See the account of this fissure in vol. i. p. 114. 

! The Vasa Vorticosa of the choroides are one of the exceptions to this. 



GENERAL ACCOUNT OF THE GREAT VEIN OF THE ARM. gg9 

manner that its branches correspond with those of the internal 
maxillary artery. Veins which correspond to some of the other 
branches of the external carotid artery, the lingual, occipital, 
&c, are often sent off near this place by the external jugular. 
They take the names of the arteries to which they correspond, 
and commonly accompany them. 

The Subclavian Vein, 

Although it originates differently on the two sides of the neck, 
is situated alike on each of them. After parting with the inter- 
nal jugular, it proceeds over the first rib, under the clavicle, and 
does not pass between the scaleni muscles, as is the case with the 
arteries, but before the anterior scalenus muscle. It soon joins the 
great artery of the arm, and proceeds before or below it to the 
axilla. In this situation, it gives off branches to the contiguous 
parts, which correspond with those given off by the artery. In 
this course it also often gives off a large branch, called the 

Cephalic, 

Which soon becomes superficial, and proceeds downwards be- 
tween the margins of the deltoid and pectoral muscles: it con- 
tinues superficial on the external side of the biceps muscle, send- 
ing off many subcutaneous branches. Near the external condyle 
of the os humeri, it generally sends oft' a branch towards the 
middle of the anterior part of the fore-arm, which is called the 
Median Cephalic, and also some other superficial branches. It 
then continues over the radius, and inclining to the back of the 
fore-arm, until it arrives at the back of the hand, where it divides 
into branches, some of which go to the thumb. 

In the axilla, the great vein, there called 

The Axillary Vein, 

Generally divides into two or three branches. One, which is 
commonly the largest, and appears like the continuation of the 
main trunk, is called 

vol. n. 25 



290 GENERAL ACCOUNT OF THE GREAT VEIN OF THE ARM. 

The Basilic Vein. 

This vessel passes down, deeply seated, to the bend of the elbow. 
It becomes superficial near the internal condyle, and divides into 
several branches. One of these generally proceeds to join the 
median branch of the cephalic, and from the union of the two 
branches is formed the median vein, which passes down near the 
middle of the anterior part of the fore-arm. This vein generally 
sends oft' a branch which proceeds internally, and anastomoses 
with the deep-seated veins of the fore-arm. 

There are frequently two other branches of the basilic vein. 
One, which is small, passes down on the ulnar side of the ante- 
rior part of the fore-arm, but does not extend to the wrist. The 
other passes down on the ulna, and gradually proceeds to the 
back of the hand, when it divides into several branches, one of 
which is generally appropriated to the little finger. 

The Axillary vein, after the Basilic leaves it, sometimes divides 
into two branches, and sometimes continues undivided. In 
either case it accompanies the humeral artery, and takes the 
name of Humeral Vein or Veins. It sends off branches which 
correspond to those of the artery, and continues to the bend of 
the elbow ; here it is so divided, that two of its ramifications ac- 
company each of the three arteries of the fore-arm. These 
ramifications sometimes communicate with each other by anas- 
tomosing branches near the elbow, and they communicate also 
with the superficial veins. 

The superficial veins of the arm are so different in different subjects, that a 
general description will rarely apply accurately to an individual case. It 
may, however, be observed that a Cephalic vein will generally be found, 
which very frequently arises from the subclavian instead of the axillary, 
and commonly continues to the hand on the radial side of the arm. The 
superficial veins, on the ulnar side of the fore-arm very frequently are 
branches of a large vein which accompanies the humeral artery to the 
elbow, namely, the basilic ; but the median vein, formed by branches of 
the cephalic and basilic veins, is very often not to be found. 



SITUATION OF THE INFERIOR VENA CAVA. 291 

Of the Inferior Vena Cava and the Veins which are connected 

with it. 

This great vessel exceeds the Superior Cava in diameter. Jt 
proceeds from the lower part of the right auricle, and very soon 
perforates the diaphragm, at a small distance in front of the spine, 
and rather to the right of the centre. As the pericardium ad- 
heres to the diaphragm at this place, the vessel appears to leave 
it abruptly. Immediately after leaving the diaphragm, it pro- 
ceeds along a groove in the posterior edge of the liver, formed 
by the great lobe and the lobulus Spigelii.* After leaving the 
liver it continues downwards, inclining backwards and to the 
left, and is soon in contact with the aorta, which is on the left of 
it. It accompanies the aorta to its great bifurcation, and divides 
in the same manner. It sends off, during this course, branches 
to the diaphragm, liver, right renal glands, the kidneys, and the 
testicles; and also the lumbar and middle sacral veins. 

The Inferior Phrenic Veins 

Are thus denominated to distinguish them from other veins, 
which are derived from the internal mammary, &c. They ge- 
nerally accompany the phrenic arteries, and are distributed in 
the same manner. 

The Hepatic Veins 

Pass off from the vena cava, nearly at right angles, into the sub- 
stance of the liver, while this vein is in the groove of that viscus, 
and before it has proceeded more than eight or ten lines from 
the heart. 

They arise from the anterior part of the vena cava, and are 
generally three in number. Sometimes there are two only, but 
then one of them divides immediately after it enters the sub- 
stance of the gland. 

The distribution of these vessels in the liver has been detailed 
in the account of that organ, and therefore need not be stated 

* Sometimes it is completely surrounded by the liver. 



292 VENA PORTARUM.-SPLENIC VEIN. 

here ; but the veins which unite to form the vena portarum, and 
the trunk of that great vein also, before it is connected with the 
liver, may be regarded as a portion of the regular venous sys- 
tem, and ought now to be considered. 

The Vena Portarum 

Passes downwards from the great sinus of the liver behind 
the pancreas, and inclining to the left. In this course it sends 
branches to the gall-bladder, the stomach and pylorus, and the 
duodenum. At the upper and posterior edge of the pancreas, 
it sends off a very large branch to the spleen, which often passes, 
with slight meanders, along a groove in the pancreas. 

The Splenic Vein 

Often sends off the Inferior Mesenteric vein, which proceeds 
downwards between the aorta and the left portion of the colon. 
It also sends off some of the coronary veins and the left gastro- 
epiploic vein to the stomach ; many small branches to the pan- 
creas; and, finally, either from the main trunk or its branches, 
before they enter the spleen, the venae breves, which pass to the 
great extremity of the stomach. Before it enters the spleen, it 
forms several ramifications, which accompany the branches of 
the splenic artery. 

After sending off the splenic, the Vena Portarum takes the 
name of 

The Superior Mesenteric Vein. 

Which is larger than the splenic and passes from behind the 
pancreas, before the transverse portion of the duodenum, into the 
mesentery ; where it accompanies the superior mesenteric artery. 

It is evident that the above described portion of the vena por- 
tarum simply performs the functions of a great vein ; but when 
it takes on the arrangements for entering the liver, it no longer 
acts like a vein, but an artery. 

The lower portion of the trunk of this vein and its ramifica- 
tions is denominated Vena Portce VentraUs. The part which 
ramifies in the liver, Vena Portce Hepatica. 



EMCLGENT VEINS.-SPERMATIC VEINS. 293 

The Capsular Veins 

Are small vessels, one on each side. That on the right passes 
from the vena cava to the right glandula renalis. That on the 
left arises from the left emulgent vein. 

The Emulgent, or Renal Veins, 

Are very large vessels, and, like the arteries, go off nearly at 
right angles, one to each kidney. 

The right emulgent vein is not so long as the left, and it is 
rather anterior to its corresponding artery. The left emulgent, 
in its course to the kidney, crosses the aorta, and is anterior to it. 

These veins pass to the sinus of each kidney, and ramify 
before they enter it. The ramifications follow those of the ar- 
teries. 

The Spermatic Veins 

Arise one on each side; the right from the vena cava, and the 
left from the emulgent vein. They proceed downwards behind 
the peritoneum, and on the psoas muscle generally divide into 
many branches, which communicate with each other as they 
progress downwards, and form a plexus denominated JJorpus 
Pampiniforme. These branches proceed in the spermatic cord 
to the back of the testis. The principal part enters the body of 
that gland ; but some of the branches go to the epididymis. In 
females the spermatic vein, like the artery, passes to the ovary, 
the uterus and its appendages, &c. 

The Lumbar Veins 

Correspond to the arteries of the same name. They arise 
from the posterior and lateral parts of the inferior cava, and 
those on the left side pass under the aorta. 

The Middle Sacral Vein 

Resembles the artery of the same name in its origin and dis- 
tribution. 

The Inferior Vena Cava accompanies the aorta to the space 

25* 



294 INTERNAL ILIAC— VESICAL VEINS. 

between the fourth and fifth lumbar vertebrae, and there it also 
divides into the two 

Primitive Iliac Veins. 

The left vein crosses behind the artery of the right side, and 
rather behind the left primitive iliac artery, which it accompanies 
until they are opposite to the junction of the sacrum and ilium, 
when it divides again, like the artery, into the internal and ex- 
ternal iliac veins. 

The Internal Iliac, or Hypogastric Vein 

Descends into the pelvis behind the artery, which it accom- 
panies. Its ramifications correspond in general with those of 
the artery, and, therefore, need not be particularly described. 

The VencB Vesicales 

Have such peculiarities that their ramifications require par- 
ticular attention. They arise from the hypogastric, very near 
the origin of the obturator, and are large, as well as numerous. 

They are somewhat different in the two sexes. In men they 
form a remarkable plexus on the lateral and inferior portions of 
the bladder, and on the vesiculae seminales. This plexus extends 
more or less to the prostate ; from it a number of veins proceed 
to the symphysis of the os pubis, which communicate in their 
course with the pudic vein. From thence arises the great vein 
of the penis, which proceeds in the groove between the corpora 
cavernosa, and terminates in the glans penis. This vein often 
divides, near the root of the penis, into two : one of which is in 
the groove, and the other more superficial.* 

In females, the venae vesicales form a considerable plexus on 
each side of the bladder and vagina. Many veins pass from 
these to the upper portions of the bladder and the contiguous 
parts, and form plexuses. The clitoris has a dorsal vein like the 

* The pudic veins accompany the arteries of that name. They communicate 
with the plexus, as above mentioned, and continue into the penis. 



BRANCHES OF THE EXTERNAL ILIAC VEIN. 295 

penis, and it originates in a manner analogous to the dorsal vein 
of the male. 

The External Iliac Vein. 

The great trunk of the veins of the lower extremity proceeds 
on the inside of the artery, under the crural arch or Poupart's 
ligament. Before it passes from under the arch, it sends off two 
branches, which answer to the circumflex artery of the ilium 
and to the epigastric artery. 

The Circumflex Vein 

Arises from the external side of the iliac vein, and passes to- 
wards the anterior end of the spine of the ilium. It divides into 
branches, which accompany those of the artery of the same 
name. 

The Epigastric Vein 

Arises from the external iliac, and accompanies the epigastric 
artery. After passing a small distance inward and downward, 
it turns up on the inside of the abdominal muscles. In the first 
part of its course it sends off some small branches to the sper- 
matic cord. 

After passing beyond Poupart's ligament, the name of the 
great vessel is changed from external iliac to 

Femoral Vein. 

It proceeds downwards at first on the inside of the femoral 
artery, but gradually changes its relative situation, so that, in the 
thigh and in the ham, it is behind or on the outside of that 
vessel. 

At a short distance below Poupart's ligament, after giving off 
some small branches to the external organs of generation, and 
to the glands of the groin, it sends off, on the internal side of the 
thigh, a very large vein, which is called the 

Saphena Major. 
This vein immediately becomes superficial, and passes down 



296 INSTANCES OF PECULIAR ARRANGEMENT OF THE VEINS. 

on the internal side of the thigh, somewhat anteriorly ; giving 
off some small branches to the contiguous parts soon after it 
originates; and many superficial veins afterwards. It continues 
along the inside of the knee and leg to the internal ankle, the 
anterior part of which it passes over. It then proceeds along the 
internal part of the upper surface of the foot to the middle, when 
it curves towards the external edge, and joins the lesser saphena. 
On the leg and foot, it also sends off many branches, which an- 
astomose with each other, and with those of the aforesaid vein. 

The femoral vein, after parting with the saphena, soon sends 
off the vena profunda, and the circumflexa also, when they do 
not arise from the profunda. These veins are generally larger 
than the arteries to which they correspond, and their branches 
are more numerous ; but they observe the same course. 

The great vein accompanies the artery down the thigh, and 
through the perforation in the adductor magnus ; but it chancres 
its relative position, so that it is placed behind or on the exterior 
side of the artery, at the lower part of the thigh. It is very often 
behind it in the ham, where, like the artery, it takes the name of 
popliteal In the ham it sends off another superficial vein, which 
seems very analogous to the basilar vein of the arm. This is 
called 

The Lesser or External Saphena. 

It proceeds from the ham over the external head of the gas- 
trocnemius, and down the outside of the leg, sending off many 
branches in its course. It passes behind the external ankle, and 
near the exterior edge of the upper surface of the foot, about the 
middle of which it inclines towards the great saphena, and forms 
with it the anastomosis already mentioned. 

The popliteal vein, after passing across the articulation, rami- 
fies like the artery, but sends two veins, which accompany each 
of the three arteries of the leg. 



In a few instances, some of the larger veins have been found 
to be arranged in a manner very different from that which is 
commonly observed. 



PULMONARY VESSELS. 297 

One case of this kind has already been mentioned in the ac- 
count of the liver,* where the Vena portarum terminated in the 
Vena Cava, below the liver, without entering into it. 

Another very remarkable instance of peculiar arrangement is 
to be seen in a preparation now in the University of Pennsyl- 
vania, in which the Inferior Cava, instead of opening into the 
lower part of the right auricle, passes behind it, in the tract of 
the Vena Azygos, and opens into the Superior Cava, in the place 
where the Vena Axygos usually communicates with that vessel, 
receiving the Intercostal Veins in its course. 

In this preparation, the Hepatic Veins communicate directly 
with the right auricle, at its lower part ; the middle and left he- 
patic veins forming one trunk before they enter, and the light 
vein passing in singly.f 

Of the Pulmonary Arteries and Veins. 

Those portions of the Pulmonary artery and veins which are 
distinct from the lungs may be described very briefly.! 

It has been already observed, that the pulmonary artery 
arises from the left and most anterior part of the basis of the 
right ventricle, and proceeds thence obliquely backwards, in- 
clining gradually to the left side for about eighteen or twenty 
lines, when it divides into two branches, which pass to the two 
lungs. This course places it under the curve of the aorta : for 

* See note to p. 93, of this volume. 

t The foregoing preparation was made by the present editor in 1814, since 
which two other anomalous cases have occurred to him. 

1819. Case 1st. The ascending cava passed into the thorax on the left side of 
the spine, and getting as far as its upper part, was joined there by the trunk of 
the internal jugular and subclavian of the left side. It there passed across the 
vessels of the arch of the aorta and joined with the descending cava. The vessels 
of the liver entered the heart at the usual place, in the lower part of the right 
auricle. 

1820. Case 2d. The trunk formed by the junction of the internal jugular and 
subclavian of the left side, instead of taking its usual course, passed down verti- 
cally, before the left branch of the pulmonary artery and before the left auricle, 
then making a slight curve between this auricle and the diaphragm joined with 
the ascending cava. — h. 

i See Fig. 71, page 298. 



p.... 



29g PULMONARY VESSELS. 

that great vessel passes over the right branch of the pulmonary 
artery, and the right side of the main trunk of it, in such a man- 
ner that it proceeds downwards between the two branches and 
behind the angle formed by their bifurcation. From this place 
of bifurcation a short liga- 
ment proceeds to the lower 
part of the curve of the 
aorta, which is almost in 
contact with it. This liga- 
ment was originally the ca- 
nal that formed the com- 
munication between the pul- 
monary artery and the aorta 
of the foetus. Each of the 
great branchesof the pulmo- 
nary artery takes a direc- 
tion backwards, and to its 
respective side. It soon 
joins the corresponding 
branch of the trachea and 
the two pulmonary veins, 
being anterior to the branch 
of the trachea, and above the pulmonary veins. It is also in- 
vested, in common with them by that portion of the pleura 
which forms the mediastinum, and thus enters into the com- 
position of the root of the lungs. 

* Fig. 71. — a, Left ventricle, b. Right ventricle, c, Right auricle. The left 
auricle is seen above the left ventricle of the same side, d, Vena cava inferior, e, 
Subclavian and jugular veins ; those of the left side unite to form the vena trans- 
versa; those of the right, to form the vena innominata; the junction of these 
larger trunks, constitute the vena cava superior or descendcns. /, Left carotid, 
g, Left subclavian artery, arising from the arch of the aorta, h, Descending aorta. 
i, k, Right subclavian, and right carotid, given off from the arteria innominata, 
which is seen arising from the arch of the aorta. I, Pulmonary artery, dividing 
into two branches, one for each lung — the left passing in front of the descending 
aorta, the right behind the aorta, where it begins to form the curve, m, Vena 
cava superior, n, Aorta, o, Left pulmonary veins, entering auricle of same side. 
The right pulmonary veins, are seen on the opposite side, p, p, Lungs, t, 
Trachea. — P. 




<Lb h 



PULMONARY VESSELS. 299 

The Pulmonary Veins are four in number — two on each side. 
In conformity to the mode of description which we have adopted, 
it may be said that they arise from the sides of the Left Auricle, 
and proceed nearly in a transverse direction, two of them to each 
lung ; where they accompany the branches of the artery and of 
the trachea, being invested by the mediastinum, in common with 
these branches. It has been observed that they differ from veins 
in general, by preserving a diameter nearly similar to that of the 
arteries which they accompany. 



PART IX. 

GENERAL ANATOMY OF THE ABSORBENT SYSTEM. 

The absorbent vessels are small transparent tubes, of a deli- 
cate structure, which exist in considerable numbers, in almost 
every part of the body. 

These tubes originate upon the surfaces of all the cavities of 
the body; and of the cellular membrane, in all the various parts 
into which it penetrates; upon the internal surface of the stomach 
and the intestines; and probably upon the skin.* 

— The Absorbent System is frequently described under the name 
of the lymphatic; but this latter term is not so appropriate as 
the former, as a generic name, since it applies only to that por- 
tion of the system spread pretty generally through the body, 
whose office it is to take up the serous and other substances (lymph) 
which are found in the midst of the organs exterior to the cavities 
of the sanguineous capillaries ; whilst another portion called the 
lacieals, originate from the villous surface of the intestinal canal, 
for the purpose of taking up and transporting the product of di- 
gestion under the form of chyle. Both the lacteals and proper 
lymphatics, however, are precisely similar in respect to structure, 
unite together so as to form common trunks, and discharge their 
contents by a common orifice into the venous system. 
— The existence of the absorbent system was unknown to the an- 
cients: for although Herophilusand Erasistratus discovered parts 
of it in their dissections of large animals, at Alexandria in Egypt, 
they were perfectly unconscious of the peculiar functions it per- 
formed in the economy ; and so little worthy of attention was their 

* See vol. i. p. 387. 



DISCOVERY OF ABSORBENTS. «JQJ 

discovery deemed, that Galen and his followers, down to the 
middle of the sixteenth century, believed that the whole function 
of absorption, even that of the nutritive materials, was performed 
by the veins. In 15G5, Eustachius observed the thoracic duct in 
the horse, which he believed to be a vein, and named vena alba 
thoracis. The chyliferous vessels were first discovered in 1622, 
by Gaspard Aselli, Professor of Anatomy at Pavia, while making 
the dissection of a living dog in the presence of some friends, 
and were seen for the first time in man by Gassendi, in 1628. 
In 1649, Jean Pecquet observed anew the thoracic duct, while 
dissecting a living dog, showed it to be the common termination 
of the chyliferous vessels, and was the first to suggest that they 
formed a distinct system of vessels. 

— Up to this time, the lacteals and thoracic duct, only had been 
the subject of observation, and the existence of the general 
lymphatic system had not even been suspected. The honour of 
having discovered the general lymphatics, has been warmly con- 
tested by three men, Olaus Rudbeck, a young Swedish ana- 
tomist, Thomas Bartholine, a Dane, and George Jolyff, an 
Englishman. To Rudbeck it is now generally admitted to be- 
long, who observed them in 1651, and in the following year, 
demonstrated them publicly before the young Queen Christina, 
of Sweden. Since that time this interesting department of ana- 
tomy has had many zealous and successful cultivators, among 
whom may particularly be mentioned, Ruysch, Meckel, Lieber- 
kiihn, the Hunters, Hewson, Monro, Cruikshank, Sheldon, Som- 
mering, Schreger, Werner, Haase, and Mascagni ; and more 
recently, especially in the field of comparative anatomy, in 
Fohman, Lauth, Lippi, Rossi, Panissa, Arnold, Miiller and 
Breschet. 

Comparison between the Absorbent Vessels and the Veins. 

— The absorbent vessels like the veins, constitute an immense 
system, which originate as minute tubes in all portions of the 
body, run from the circumference to the centre, and converge 
into two or more canals of considerable size, which open into 
large venous trunks. Like the veins, also, the absorbents are di- 
vol. ii. 26 



302 COMPARISON BETWEEN THE ABSORBENTS AND THE VEINS. 

vided, into two portions or couches; a superficial, which is spread 
extensively immediately under the skin, and accompanies in ge- 
neral the superficial veins of the limbs ; and into a deep-seated 
or profound, which accompany the deep-seated arteries and 
veins. Like the veins, too, the absorbent vessels are provided 
abundantly with valves. 

— Here the analogy between the two systems of vessels cease. 
The absorbents differ from the veins, in having their course in- 
terrupted from time to time, by the lymphatic glands ; by the 
mode in which they run, not uniting successively into branches 
and into trunks like the veins, but each running as it were an in- 
dependent course from their origin to near their termination, and 
not enlarging much in diameter, though they anastomose fre- 
quently with each other. The fluid which circulates in the veins, 
is yet, though in a diminished degree, under the influence of the 
heart (vis a tergo) ; the fluid of the absorbent vessels, appears to 
be exclusively under the influence of the walls of the vessels 
themselves. The origin or radicles of the veins have been clearly 
shown by the microscope, to be from the arteries through the 
intervention of the capillary vessels ; whilst the origin of the ab- 
sorbents though yet involved in much obscurity, on account of 
their tenuity and the transparency of the fluids which they carry, 
is believed to be wholly different. — 

The absorbents which originate in the Lower Extremities and 
the Cavity of the Abdomen, unite and form a large trunk called the 
Thoracic Duct, which proceeds through the thorax, and termi- 
nates in the left Subclavian Vein, at its junction with the Internal 
Jugular. Those of the Left Upper Extremity, the Left side of 
the Head, and the contiguous parts, form a trunk which termi- 
nates in the same place. While the remaining absorbents, or 
those of the Right Upper Extremity and the Right side of the 
Head, fyc. also form a trunk which terminates in the correspond- 
ing part of the Right Subclavian Vein. 

The absorbent vessels of the middle size, which arise from 
the union of the small vessels, and unite to form the larger, in 
their progress to these large vessels, pass through certain bodies 



STRUCTURE OF THE ABSORBENT VESSELS. 303 

which have been denominated Conglobate Glands, and may be 
considered as appendages of the absorbent system. 

The absorbent vessels are composed of two coats, which are 
thin, but dense and firm, and also elastic. The coats of the tho- 
racic duct may be separated from each other. The internal sur- 
face of the exterior coat is fibrous. The internal coat is a deli- 
cate but strong membrane. There is great reason to believe 
that the above mentioned fibres are muscular, or at least irritable; 
for the absorbent vessels have been observed, by Haller, to con- 
tract upon the application of strong sulphuric acid. They have 
also been observed to propel their contents with considerable 
rapidity, by their own contraction, independent of pressure, or 
of motion communicated by any other body. 

Blood-vessels are sometimes observable in the coats of the 
larger absorbents, in injected subjects. The vascularity of these 
tubes may also be inferred from the inflammation which fre- 
quently takes place in them. 

Nerves have not been traced into their texture ; but the ab- 
sorbents seem to be painful when they are inflamed, and, there- 
fore, it is probable that they are supplied with nerves. 

The absorbent vessels are very generally supplied with valves, 
which are much more numerous in some of them than in others; 
and are different in their number, in the same vessels, in different 
subjects. 

Very frequently there are several valves in the course of an 
inch: sometimes a valve will not appear in the course of several 
inches. In the Thoracic Duct the number of valves is very dif- 
ferent in different subjects. These valves are folds or plaits of 
the internal membrane, and are of a semicircular form. There 
are commonly two of them together originating from opposite 
sides of the vessel. 

The absorbents are generally somewhat dilated on the side of 
the valve which is next to their termination, and this occasions 
their knotted appearance when they are injected. The object of 
this valvular structure seems to be the prevention of retrograde 
motion of the contained fluid, in consequence of lateral pres- 
sure. 



304 COMMENCEMENT OF THE ABSORBENTS. 

Where the different trunks of the absorbents open into the 
veins, there are one or two valves to prevent the regurgitation of 
the blood into them. 

The valves of course prevent the injection of the branches of 
these vessels from their trunks. In some animals the valves 
have sometimes been ruptured, or forced back ; and the absorb- 
ents have been injected in a retrograde direction. There are 
but two or three instances upon record where this has been 
practicable in the Human Subject. 

In consequence of the impracticability of injecting the small 
branches from the larger, the absorbent vessels cannot, generally, 
be demonstrated at their commencement, or origin. It is, how- 
ever, to be observed, that the Lacteals, or Absorbents of the In- 
testines, appear no way different from other absorbents; and 
they have been seen distended with chyle, from their com- 
mencement, in certain subjects who had died suddenly. Their 
origins have been described very differently by different obser- 
vers. 

Mr. Cruikshank describes them as originating on the surfaces 
of the villi, by a number of very small radiated branches with 
open orifices ; which branches soon unite to form a trunk. 

Lieberkiihn believed them to commence in the form of an 
ampullula. (See page 43 of this volume.) 

The second Monro also believes that the absorbents begin 
by very small tubes, with open orifices in several species of 
fish.* 

It is stated by Dr. Sommering, upon the authority of Haase, 
a German anatomist, that when mercury is forced backwards in 
the absorbent vessels of the foot and the heart, it has sometimes 
escaped on the surfaces of those parts. The probable inference 
from these facts is, that those vessels originate by open orifices 
on the surfaces of the heart and foot. 

Origin of the Absorbent Vessels. 
— Mascagni, who devoted the greater part of his life to the 

* See his work on the Structure and Physiology of Fishes, p. 34. 



ORIGIN OF THE ABSORBENT VESSELS. 395 

study of the absorbent vessels, was able to demonstrate their 
existence in every part of the body, with the exception of the 
substance of the brain, the spinal marrow, the eye, bones, pla- 
centa, and umbilical cord. Within a recent period Fohman* has 
succeeded in detecting them on the surface of the encephalon, in 
the meninges, in the plexus choroides, in the placenta, and in the 
umbilical cord ; Arnoldf has seen them upon many of the tissues 
of the globe of the eye; and Cruikshank, Sommering, and 
Bonamy,J have succeeded in tracing them into the interior of 
the bones. There can, therefore, at the present moment, be no 
doubt of their general distribution throughout, the body. 
— On the surfaces of the different membranes of the body, these 
vessels have, however, been found to be most numerous, and 
Mascagni was induced to believe that these membranes, and es- 
pecially the serous and the cellular, the latter of which forms the 
web-work of the whole body, consisted of a net-work of ab- 
sorbent vessels. But he does not explain himself clearly in 
regard to the point in question, viz. the mode in which these ves- 
sels have their origin. 

— The great difficulty in determining this question in man and 
the superior animals, is the obstacle which the valves present to 
the injection of mercury backwards and towards their roots: for 
if this could be effected, as it has been in the excretory ducts of the 
glands, the anatomist, by the aid of the microscope, would pro- 
bably soon be enabled to solve the difficulty, and especially, as 
there is reason to believe that the radical absorbents have a 
diameter superior to that of the sanguineous capillaries. In 
the absence, therefore, of all positive knowledge upon the subject, 
there has been much room for speculation; — some believing them 
to originate from the arteries, — some by open mouths or gaping 
orifices, — and some by a net-work, in which the vessels, tracing 

* Memoires sur les Vaisseaux Lymphat. etc. etc. Liege, 1833 ; and, Sur les Vais- 
scaux Absorb, du Placenta et du Cord Umbilicale. — p. 

t Anatomische und Physiol. Untersuchcmgen uber das Auge des Menschen. 
Heidclburg, 1832.— p. 

I Cruvielhier Anat. Spec. T. iii. 

26 * 



306 GENERAL ANATOMY OF THE ABSORBENT SYSTEM. 

them towards their origin, seem to anastomose again and again 
with one another. 

— The first opinion was derived from the fact first noticed by 
Cowper, Cheselden, and F^rrein, that in making delicate injec- 
tions of some parts of the body, the injecting matter, will pass 
occasionally from the arteries into the lymphatics; and Breschet* 
has observed the same thing to occur when an injection has been 
pushed at the same time in several of the smaller branches of the 
veins, in the direction of their roots. The researches of Panissa,f 
Miiller, and others, have shown that this takes place but sparingly 
in any part of the body, and in general, only when considerable 
force is used, and that in some portions it cannot be effected at 
all. So that this communication with the arteries, cannot be 
looked upon as the common origin of the absorbents, which are 
so very numerous ; and in many instances is most probably 
produced by a laceration of the tissue from the force of the 
injection, by which some of the injected fluid insinuates itself into 
a ruptured absorbent vessel, or by a passage through the pores 
in the parietes of the vessels, as Fohman has suggested. 
— The origin by open mouths or gaping orifices, which has been 
maintained by Lieberkiihn, Cruikshank, Cruvielhier, Magendie, 
etc., and only with respect to the lacteals, does not appear to 
be better founded, and is probably produced by a laceration of 
the parts; since Rudolphi, Panissa, Breschet, Fohman, and 
Lauth, in experiments made expressly to determine this point, 
have never observed it as a normal state, either in the injection 
of dead bodies, or in the microscopical observations of the trans- 
parent parts of living animals, or in observations like that of 
Cruikshank, made by Lauth and Krause, on the lacteals of a 
human subject, that were found distended with chyle. (See vol. 
ii. p. 67.) 

— The mode of origin by a mesh or net-work, is not only that 
which is best supported by the concurrent testimony of recent 
observers, but appears also to have been that supported by 
Mascagni. This appears to be demonstrated by the three only 

* Le Systeme Lymph, etc. par G. Breschet. Paris, 1836. — p. 
t Osservationes Antrop. Zootomico Fisiologichc. By Prof. Paaissa. Pavia, 
1833.— p. 



ORIGIN OF THE ABSORBENTS. gQ7 

modes in which the capillary absorbent vessels have been made 
obvious to the eye. That of Mascagni, in which a serous cavity 
was filled with a coloured fluid, with which the absorbents of the 
lining serous membrane filled themselves, and thus became 
visible; that of Lauth, which consisted in filling the minute ab- 
sorbents with mercury, and gently pushing it with the handle of 
a scalpel towards their capillary extremities, in which, as in the 
veins, the valves cease to exist ; and that of Cruvielhier and 
others, which consists in puncturing superficially the surface of 
the skin, or of the mucous and serous membranes, with the point 
of a mercurial injecting tube, when the mercury will be seen 
gradually to dilate the orifice into a little sac, and then to in- 
sinuate itself into the absorbent vessels. The absorbents injected 
by either of these modes appear to constitute a dense net-work 
or plexus of vessels, which communicate on the opposite side of 
the membrane with larger absorbent trunks, in which valves begin 
to be visible. From the injected membrane, the cuticle of the 
skin, or the epithelium of the mucous tissue may be removed by 
maceration, without liberating the mercury, which is thus shown 
to be confined not merely in the cells of the cellular tissue, but in 
a system of tubes. 

— Fig. 72, is a specimen of the lymph- to " 

atics of the mucous membrane of the 
stomach, prepared in this way after ^: : 
Breschet; and Fig. 73, page 311, of the 

lymphatics ot the mucous surface ot the -;. -.Jra h 

glans penis, and of the skin of the scro- 
tum. The vessels thus injected present fj 
very much the appearance of a mesh of ' ' ' ''"' 

arteries and veins, for which, no doubt, they have been sometimes 
mistaken. 

— But the lymphatic net-work is evidently seated above the 
blood-vessels, for if the latter be subsequently injected, they never 
rise up so as to cover the former; and where the blood-vessels 

* Fig. 72, is a representation of the origin of the absorbents of the stomach, after 
Breschet. a, Superficial layer. 6, Deep-seated layer. — p. 



308 GENERAL ANATOMY OP THE ADSORBENT SYSTEM. 

have first been filled, the lymphatics may be subsequently injected 
above them. In the mucous membranes provided with epithelium, 
the situation of the superficial absorbent net-work is precisely the 
same as in the skin; but in mucous membranes unprovided with 
epithelium, or rather in which the epithelium exists in a state of 
undried mucus, the situation of the lymphatic net-work is more 
naked, a condition which is eminently favourable for the ac- 
complishment of the function of absorption. 
— Each of the villi of the mucous membranes, are now believed 
to be nothing more than delicate elevations of the mucous mem- 
branes, comprising separate loops of the sanguineous and absor- 
bent vessels, and probably nervous fibrils, covered by mucus. 
The lymphatic vessels have the same mode of origin in the lining 
membrane of the cavities of the heart, as well as on the exterior of 
that organ as has been proved by Lauth, Bonamy, and Cruviel- 
hier,* who succeeded in injecting them. 

— The origin of the lymphatic vessels, from the midst of the 
nervous, muscular, and glandular structure, is not, from the very 
nature of the parts, easily susceptible of demonstration. Nothing 
positive, therefore, is known in regard to it, and it is most proba- 
ble that Mascagni was right in his suggestion, that the numerous 
vessels which issue from the parts, originate in the cellular tissue 
which form the woof of the organs. 

— The origin of the lymphatics from the cellular tissue and serous 
membrane, which is but a modification of the cellular, is certainly 
more general than that from any other tissue of the body, and 
there is much reason to believe, that it is the principal point 
from which they arise — the soil in which their radicles are found ; 
and in the different organs of the body where lymphatics are 
known to originate, it is most probable, though not yet fully de- 
monstrated, that it is from the cellular woof that they take their 
rise. In fact, the organs in which this tissue does not enter, are 
the only ones from which no lymphatics originate, viz. the nails, 
horns, epidermis, ivory of the teeth, etc. Mascagnif and Cru- 
vielhier have observed, in respect to the cellular tissue and the 

* Anat. Speciale, torn. iii. — p. 

t Vasor. Lymph. Corp. Human. Hist, et Iconogr. Sienne, 1787 p. 



ORIGIN OF THE ABSORBENTS. gQQ 

serous membranes, so many lymphatics in their combination as 
to be induced to believe that they are formed of lymphatics. 
The microscopical researches of Fohman, Arnold, and Trevira- 
nus upon this subject, have led them nearly to the same conclu- 
sion ; the two first believing that the cellular tissue acts the part 
of a sponge to the absorbents which have their radicles in it, and 
that its filaments are probably composed of very minute element- 
ary lymphatic vessels. Treviranus,* in some very recent obser- 
vations in comparative anatomy, (especially in the tortoise) has 
satisfied himself, by the use of a glass of very great magnifying 
powers, that the absorbents take their origin in the cellular tissue 
which is composed of elementary cylinders, closely interlaced 
together, some twisted, some zigzag in shape, and of such mi- 
nuteness as to have a diameter only the 0.0016, to 0.0002 of a 
millimetre-! Some of these unite together, and form larger 
cylinders, which go out from the mass, unite with others of the 
same kind, and thus form trunks of 0.001 to 0.0023 of a millime- 
tre in diameter, which have the appearance of lymphatics, and 
open into the lymphatic vessels. Thus he believes, that when ulti- 
mately analyzed, the lymphatic vessels will be found to originate 
on all the free surfaces of the body, in the midst of the tissues, 
as well as in the intestinal villi, by elementary tubes belonging to 
the cellular tissue, which constitutes the basis or web-work of the 
organs, and which tubes have appeared to him on the villi and 
free surfaces of the body, to terminate in vesicles which seemed 
in some parts to be pierced with a hole. 

— However the facts may hereafter be found to be, in regard to 
these researches of Treviranus, for the high magnifying powers 
employed would necessarily render him liable to optical illusions, 
we are fully justified, at the present advanced stage of anatomical 
science, in considering the absorbents as not arising either from 
the arteries or veins, but as separate vessels in the meshes of the 
cellular tissue, which divide, unite, re-divide, and anastomose 
together, again and again, till they seem to occupy the whole 

* Bertrng-e Zur Auf klaerung der Erscheinungen und Gesetze, dcr organitschen 
Lebens. 1836, page 100. — p. 

t A millimetre equals the 0.039379 part of an English inch. — p. 



310 GENERAL ANATOMY OF THE ABSORBENT SYSTEM. 

mass of the tissue, and convert both the proper cellular and 
serous membranes, into mere spongy absorbing surfaces. 
— It would seem that absorption took place in consequence of 
the permeability of this net-work structure of the tissues to the 
fluids in which the absorbents are bathed, (as has been so clear- 
ly shown by E. Edwards* to be the case in the amphibia?,) 
whether the fluid consists of effused serum, escaped through the 
pores of the blood-vessels and mixed up with the effete molecules 
of the organs, or of ecchymosed blood, or of purulent collections ; 
and that this permeation is aided by an attraction through the 
walls of the vessels into their interior, called endosmosis by Du- 
trochet, where the fluid is placed under the influence of the ab- 
sorbents, and is passed onwards towards the thoracic duct. If 
the assertions of Treviranus should be found correct, it might be 
considered as being pumped up through a series of the minutest 
capillary tubes. 

— The contractility of the absorbent vessels is very evident, and 
exists even for many hours after death, as may be seen by open- 
ing an animal shortly after it has been killed. Their force of 
resistance is also very considerable compared with the arteries 
and veins of the same diameter. 

— In the inferior extremities it is considered to be to that of the 
arteries in the proportion nearly of 10 to 3. These vessels are 
very elastic, and one which is almost imperceptible to the naked 
eye, becomes, when fully distended with mercury, half a line in 
diameter. 

— This elasticity resides in the external coat of the vessels, 
which is no longer considered muscular, but as a sort of yellow 
elastic tissue, somewhat like the structure of the dartos, which 
allows the lymphatics to extend themselves to a great degree 
without breaking, and subsequently to return upon themselves 
and propel their fluid contents onwards. 

— Absorbent Glands do not exist at all in reptiles and in fishes. 
The first trace of them is met with in birds, where they are formed 
merely by the absorbent vessels, interwoven and reticulated in 
the form of plexus. In man, their structure appears in fact to 
be the same, but the meshes are minute. Many anatomists, as 

* De l'lnfluence des Agens Physiques sur la Vie, etc. — p. 



ABSORBENT GLAXD5. 

Fig. 73.* 



311 



h ■■ '■/■/'""/ / 




-./' 



I. b 




Malpighi, Cruikshank, and Werner, believed there existed par- 
ticular follicles, forming round cells, with their walls in the in- 

* Fig. 73 — Represents the inguinal region of a young infant, the prepuce slit 
open, in order to expose the glans, (from Breschct.) a, a, Two of the superficial 
inguinal lymphatic glands, b, b, Efferent lymphatic vessels, filled with mercury, 
terminating in these glands, c, c, The same lymphatic vessels, laid bare in the 
groin, to exhibit, their course in the subcutaneous cellular tissue, d, d, The same 
vessels penetrating the tissue of the skin, where, by their ramifications and anasto- 
moses, they form a dense net- work, e, e, which, properly speaking, constitutes their 
origin. This net-work is on the exterior face of the cutis vera, and is covered only by 
the epidermis. /,/, Arterial branches, distended with fine coloured injecting mat- 
ter, in order to render it certain that the vessels filled with mercury, are lymphatic, 
and not sanguineous vessels. The termination of these vessels in the lymphatic 
glands, moreover, prove their character, g, g, Prepuce slit open on its upper part, 
in order to show its internal face, upon which is seen a beautiful net-work of lym- 
phatics in the cutaneous tissue, which is here modified so as to appear like mucous 
membrane, h, h, Net-work of lymphatics in the mucous membrane covering the 
glans penis. The efferent vessels of the two inguinal glands are not seen in this 
figure, as they arise from the opposite side of the glands, and run deep to get 
into the cavity of the abdomen, below Poupart's ligament. — r. 



312 GENERAL ANATOMY OP THE ABSORBENT SYSTEM. 

terior of the glands, with which the vasa inferentia and efferentia 
communicated, and upon wh ' h lie blo< d-vessels ramified; but 
nearly all modern anatomists who have investigated this subject, 
adopt the opinions of Ruysch, Hewson, Meckel, and Mascagni, 
that these cells are nothing but artificial dilatations of the absorb- 
ent vessels, and that the entire structure of a lymphatic gland 
consists of convoluted lymphatic vessels, densely arranged, and 
anastomosing freely togeth r, over which arteries and veins 
ramify, the whole b< ing embraced by common cellular tissue, in 
the form of a capsule. 

— Magendie has called the at entinn of the profession to a fluid 
peculiar to the mesenteric glands, and which was known previ- 
ously to anatomists under the name of the succus proprius. But 
Lauth has shown that this fluid does not exist in the interlobular 
cellular tissue, and is in fact but a part of the common contents 
of the blood-vessels, and found in all the other lymphatic glands. 
— The absorbent glands are softer and larger in children and 
young persons than in adults, and se m to diminish in number in 
old men. There is nothing in this fact, according to Lauth, that 
should surprise us, since the glands are made up only of convo- 
luted vessels, which, like the sanguineous capillaries, become less 
and less active, and are here and there obliterated in the atrophy 
attendant upon extreme old age. 

— It is as yet considered very doubtful, whether the absorbents 
have any communication with the secreting ducts of glands. In 
injecting the excretory ducts of the glands with mercury, espe- 
cially those of the mamma, testicle, and liver, it is very usual to 
find some of it escaping into the absorbent vessels. This, which, 
to all appearance, would seem to prove their direct connexion, is 
notwithstanding considered by many distinguished anatomists, 
as caused by a rupture of some part of the glandular structure, 
and that the mercury found its way into the openings made by 
the laceration in the absorbent vessels. But the communication 
between these vessels and the excretory ducts, takes place so 
readily, in the injection of the latter, and so much without the ap- 
pearance of extravasation, as to render it most probable that there 
exists some anastomosis between them. The same degree of 



TERMINATION OF THE ABSORBENTS. 3] 3 

doubt exists in regard to the connexion between the absorbents 
and small veins. It has been chiefly alleged to exist between 
them, in the excretory glands of the body, and in the absorbent 
glands themselves; in all which parts, the friability of their struc- 
ture renders them liable to laceration, by the pressure from a mer- 
curial column, or by ordinary minute injection thrown in with 
force. Though the fact is very evident, that many of the absorb- 
ents may be filled by injection of the ducts of the secernent 
glands, and that mercury passes with extreme facility from the 
lymphatics of the absorbent glands into the veins, the weight of 
testimony, is certainly at present in favour of its taking place 
only in consequence of a laceration of tissue. The statements 
of Lippi,* in regard to the free communication, which he has 
described between the lymphatic vessels and veins, are now dis- 
regarded, in consequence of its having been shown by Fohman, 
Panissa, and Breschet,f that he had mistaken in his investigations 
capillary veins for lymphatic vessels. 

— The opinion in regard to the termination of the absorbents, 
since the many alleged venous communications of Lippi have 
been disproven, has reverted now to that entertained formerly, 
by Hewson, Cruikshank, and others ; namely, that the absorb- 
ent and venous systems, can be considered as connected only 
by the principal lymphatic trunk, the thoracic duct, which opens 
into the left subclavian vein, and by the right brachio-cephalic, 
and other branches, which open into the internal jugular and 
subclavian of the right side. All other communications which 
take place between them may be received as exceptions to the 
normal structure. 

— The most frequent of these, are the branches between the 
thoracic duct, and vena azygos. In many amphibia and reptilia, 
lymphatic hearts,orcontractiledilatationsof the absorbent vessels, 
have been discovered by Miiller, which assist in the circulation 
of the lymphatic fluid.J Nothing analogous to them, has, how- 
ever, been discovered in man. — 

* Illust. Fisiol. c Pathol, del Sistcm. Limfat. Chil. etc. Firenze, 1825.— p. 
t Vide Breschet, sur la Systemc Absorbant. 

t Sec an interesting paper on this subject by Dr. Allison of Philadelphia— Amer. 
Jour. Med. Science, Aug. 1838. 

VOL. II. 27 



314 CONGLOBATE GLANDS. 

The bodies connected with the absorbent vessels, which are 
called Conglobate Glands, are generally of a roundish, or irre- 
gular oval form, and somewhat flattened. They are of various 
sizes, from two lines in diameter to more than twelve. Their 
colour is frequently whitish, but sometimes it is slightly inclined 
to red. They are invested with a covering of cellular mem- 
brane, which appears like a membranous coat; and they are 
connected to the contiguous parts by a loose cellular substance. 
When the absorbent vessels connected with these bodies approach 
near to them, they divide into a number of ramifications, most 
of which enter into the substance of the gland, while some of 
them run over it. On the opposite side of the gland a number of 
branches go out, which unite and form trunks similar to those 
which entered the gland. The vessels which enter the gland 
are called Vasa inferentia, and those which go out of it Vasa 
efferentia. 

These vessels are generally much convoluted in the substance 
of the glands, so that those bodies sometimes appear like a mere 
convolution of absorbent vessels. There has been much diver- 
sity of sentiment respecting the structure of these organs.* 

The absorbent vessels, in the different parts of the body, ge- 
nerally contain fluids resembling those which are found in those 
parts. Mr. Hewson opened the large absorbents in many living 
animals of different kinds, and found that they contained a trans- 
parent fluid, which coagulated when exposed to the open air. 

The arrangement of these vessels resembles that of the veins 
in several respects. Many of them are superficial ; but there 
are also deep-seated absorbents which accompany the blood- 
vessels. 

Of the Chyle. 
— Under this name we designate the fluid, carried by the ab- 

* Mr. Abernetby states, that the mesenteric gland of the whale consists of large 
spherical bags, into which a number of the lacteals open. Numerous blood-vessels 
are ramified on the surfaces of these cysts ; and injection passes from them into 
the cyst. He also found cells in the glands of the absorbent vessels, in the groin 
and the axilla of the horse. See Philosophical Transactions, for 1796, Part I. 



OF THE CHYLE. 31 5 

sorbcnts of the intestinal canal during digestion ; in the inter- 
vals of digestion, the trunks of the same vessels in the mesen- 
tery are filled only with the ordinary lymph. These vessels 
of the intestinal canal are called lacteals, in consequence of their 
white appearance when distended with chyle. The lymph proper, 
is a fluid taken up by the radicles of the general lymphatic sys- 
tem, and is mixed with the chyle in the thoracic duct. Chyle is 
limpid in birds, a little opaque in herbivorous animals, and very 
opaque in the carnivorous, including man. The opacity of the 
chyle, appears to depend upon the great number of globules sus- 
pended in it, which appear to be round in birds and all the 
mammalia, notwithstanding, the blood globules are elliptical in 
birds, and flattened in man. (See vol. ii. p. 218.) According to 
Miiller, the chyle globules are to be found in the first radicles of 
the lacteals, as he saw them distinctly in the calf ; this favours the 
opinion that they are not formed in the vessels themselves, but 
are probably taken in in the state of globules during digestion, and 
are probably the results of the disintegration of the alimentary 
matter, by the digestive process. The chyle has a spermatic odour, 
an alkaline taste, and varies in many respects, according to the 
nature of the aliment subjected to the action of the digestive 
organs. According to Magendie, Tiedemann and Gmelin, the 
chyle from aliments containing an abundance of fatty matter, is 
very white and full of oily particles, which, when the fluid is 
drawn from the vessels, float on its surface like a sort of cream: 
while that formed from food possessing little or no fatty matter, 
is more opaque, and exhibits but little or no creamy covering 
upon its surface. 

— The chyle evidently undergoes a change as it ascends in the 
thoracic duct. It exhibits more and more of a rose tint in place 
of its creamy colour, and is more coagulable and more assimi- 
lated in appearance to the blood, the nearer to the top of the 
thoracic duct, that we extract it for examination during the act 
of digestion. During that period the duct is filled chiefly with 
the contents of the lacteal absorbents, but little of the general 
lymph of the body, being at that time transported to the duct. 
When withdrawn from the duct, chyle coagulates of itself, and 



316 OF THE LYMPH. 

the action of the air heightens greatly its rosy hue. The coag- 
ulation takes place in this fluid, from the same causes that it does 
in the blood ; from the fibrine which exists in a state of solution 
in the recent chyle, returning to the solid state, and inclosing a 
part of the globules. 

— The serum in which the coagulum floats, is a solution of albu- 
men, containing likewise some of the globules, and at the same 
time, has floating upon its surface a layer of fatty particles. In 
the lungs, where the chyle passes, mixed with the venous blood, 
the final change is effected, so that the chyle can no longer be 
distinguished from the sanguineous fluid. The opaque colour 
of the chyle in the lacteals, according to Tiedemann and Gmelin, 
is dependent not only upon the number of the globules it contains, 
but in part, also, upon the minutely divided particles of fat which 
are suspended in it. 

Of the Lymph. 

— The term lymph has been very loosely applied by anatomists 
and physiologists, not only to the fluids of the lymphatic vessels, 
but to the serum of the blood, to the transparent fluids of the 
serous cavities, and to many albuminous and fibrinous exudations. 
Latterly it has been more appropriately confined to the contents 
of the general lymphatic system. 

— It has been collected for examination from the thoracic 
duct, and from the absorbent trunks of the upper extremities, 
head, and neck, in many animals after several days starva- 
tion, when no materials had been afforded for the formation 
of chyle ; it has also been very recently obtained by Muller. 
from the human subject, in the case of a young man in the hos- 
pital at Bonn. This individual had received a cut on the back of 
the foot which could not be made to cicatrise, and the divided- ab- 
sorbents threw out, when pressed upon, a large quantity of lymph, 
which was transparent, inodorous, saline to the taste, with alca- 
line properties, and which, in about ten minutes after being col- 
lected, formed a delicate coagulum resembling a spider's web. 
The lymph, when examined with the microscope, presented many 
globules, much less abundant, however, and smaller than those of 



COMPARISON BETWEEN CHYLE AND LYMPH. 317 

the blood. During coagulation part of these globules, were in- 
closed in the clot, but the greater part were suspended in the 
serum. 

— The coagulation was evidently produced by the solidification 
of a substance previously fluid, which is considered to be fibrine, 
and which, in passing to the solid state, enveloped a certain por- 
tion of these globules, that was before free. 

Comparison between Chyle and Lymph. 

— Both contain globules ; but they are few in number in the 
lymph, and abundant in the chyle. Both contain fibrine in solu- 
tion. The most important difference between these fluids, con- 
sists in the fatty matter, which the chyle holds in solution, and 
which does not exist in the lymph. The other constituents, fibrine 
albumen, salts, etc., are much the same in both. 
— In regard to the disposition of the colouring matter which is 
generally found in chyle, and sometimes even in lymph, whether 
it is in a state of general solution, or attached to the globules, as 
in the case of the blood, we literally, as Breschet, has observed, 
know nothing as yet. Between these two fluids there are, as 
may be observed, many points of analogy with the blood. The 
chyle contains new globules formed by the digestion and dis- 
integration of the alimentary matter, and which are destined, 
when they have received the last finish of assimilation in their 
passage through the lungs, to constitute the nuclei of the red 
particles of the blood. 

— The lymph also contains globules formed from the wreck of 
the old materials of the body, as they exist in the molecular state, 
in the different tissues of the body ; the size of which globules, as 
has been shown by some observers, is about equal to that of the 
nuclei of the red particles of the blood, and which are destined 
to be thrown out from the body, as being worn out and worthless, 
or to be reinstated by the action of the lungs, into the same condi- 
tion that they were formerly, before they had been deposited 
from the blood to constitute the atoms or molecules of the different 
organs. 

27* 



318 SUPERFICIAL ABSORBENTS. 



CHAPTER X. 

OF THE ABSORBENTS OF THE LOWER EXTREMITIES, THE ABDOMEN. 
AND THE THORAX. 

Under this head are arranged the ramifications of all the 
vessels which unite to form the Thoracic Duct. 

Of the Absorbents of the Lower Extremities. 

These absorbents, like the veins, are superficial and deep- 
seated. The superficial lie in the cellular membrane, very near 
the skin ; and form an irregular net-work which extends over the 
whole limb. They are, however, most numerous on the internal 
side. 

The deep-seated accompany the arteries like the veins, and 
there are two at least to each artery. 

The Superficial Absorbents 

Have been injected from the toes so as to form a net-work, 
which occupies the upper surface of the foot. They have also been 
injected in a similar manner on the sole. Those on the upper 
surface of the foot generally proceed upward on the anterior 
and inner side of the leg; but some of them pass on the external 
side of it. Those on the sole are continued on the back of the 
leg, but communicate very frequently with the anterior vessels. 
Some of the absorbents from the outside of the foot and leg 
enter into some of the popliteal glands, soon to be described ; 
but they are not numerous ; and the principal number continues 
up to the glands of the groin. The absorbents which originate 
on the suface of the thigh, as well as those which pass over it 
from below, incline gradually along the anterior and posterior 
surface, to the internal side of it; on which they proceed in 
great numbers, and very near to each other to the inguinal 



ABSORBENTS OF THE INFERIOR EXTREMITIES. 319 

glands. Superficial absorbents proceed also from the buttock 
and lower part of the back, from the lower part of the abdomen, 
the perineum and the exterior of the genital organs, to these 
glands. 

The Deep-seated Absorbents 
Are named from the arteries they accompany. 

The Anterior Tibial Absorbents. 

The anterior tibial artery is generally attended by one which 
comes with it from the sole, and by another which commences 
on the upper surface of the foot. The first mentioned absorbent 
continues with the artery. The last often passes through an 
aperture in the interosseal ligament, about one-third of the dis- 
tance from the ankle to the knee, and accompanies the fibular 
artery, while the anterior tibial artery is joined by other absor- 
bents about the same place. In some instances a small absorbent 
gland occurs in this course at a short distance below the knee. 

The Posterior Tibial Absorbents 

Have been injected from the under side of the toes. They 
accompany the ramifications on the sole of the foot; and, after 
uniting, continue with the main trunk up the leg, where they 
enter the popliteal glands. 

The Peroneal Absorbents arise also from the sole of the foot, 
and its external side. They accompany the peroneal artery, 
and terminate in the popliteal glands, which receive also the 
absorbents from the knee and ham. 

From these glands four or five absorbent vessels proceed 
which accompany the great blood-vessels of the lower extremity; 
and, proceeding with them through the aperture in the tendon of 
the adductors, continue upwards until they enter some of the 
glands of the groin. 

The glands of the ham and groin, which are so intimately 
connected with the absorbents of the lower extremity, are very 
different from each other. 



320 ABSORBENTS OF THE INFERIOR EXTREMITIES. 

The Popliteal Glands, or those of the Ham, are but three or 
four in number, and very small in size. They are generally 
deep-seated, and very near the artery. 

The Inguinal Glands vary in number from eight to twelve or 
more. They are superficial and deep-seated. The superficial 
communicate principally with the superficial absorbents. The 
lowermost of them are at some distance below Poupart's liga- 
ment, and the uppermost are rather above it. They are exterior 
to the fascia of the thigh. Their number is generally six or eight, 
while that of the deep-seated is but three or four. 

The superficial absorbents from below, approach very near to 
each other, and enter these glands. They are commonly dis- 
tributed among three or four of the lowermost; but some of them 
pass by these, and proceed to one that is higher up ; and some- 
times there are absorbent vessels which pass to the abdomen 
without entering into any of the glands of the groin. 

The deep-seated absorbents pass into the deep-seated glands, 
which, as has been already observed, are but few, and lie very 
near the artery, under the fascia of the thigh. The two sets of 
glands are connected with each other by many absorbent vessels 
that pass between them. The vessels which finally go out of 
these glands are considerably less in number than those which 
enter into them. They proceed under Poupart's ligament, and, in 
some instances, a large proportion of them passes through three 
glands which lie below this ligament, and are often so arranged, 
that they lie on each side of the great femoral vessels, and above 
them. One very frequently is found on the inside of the femoral 
vein, in the vacuity between it and the internal part of the liga- 
ment. All the absorbents of the lower extremity, however, do 
not enter these glands. Some pass along the great vessels and 
enter other glands near the margin of the pelvis. Some, also, 
descend a short distance into the pelvis, and unite with vessels 
that are passing from the pelvis to the plexus and the glands that 
surround the external iliac. 

The absorbents which proceed from the glands last mentioned, 
joined to those which pass under Poupart's ligament without 
entering these glands, and some which come from the pelvis, 



INGUINAL AND EXTERNAL ILIAC GLANDS. 32 1 

form a large plexus, which almost surrounds the external iliac 
vessels, and contains many glands. 

These External Iliac Glands vary in their number from six to 
ten or twelve. They lie on the side of the pelvis, in the course 
of the external iliac vessels, and some of them are of considera- 
ble size. These glands and the plexus of absorbents, extend in 
the track of the iliac vessels, to the first lumbar vertebra. In 
this course they are joined by the plexus which comes from the 
pelvis; and soon after they arrive at the Lumbar Glands, which 
form a very large assemblage, that extends from the bifurcation 
of the aorta to the crura of the diaphragm. 

These glands lie irregularly on the aorta, the vena cava, and 
the lumbar vertebrae. Most, if not all, the absorbents above 
mentioned pass through some of them ; and from the union of 
these absorbents, some of the great branches, which unite to form 
the thoracic duct, are derived. 

In this course, from the thigh to the lumbar glands, these ab- 
sorbent vessels are joined by several others. The Superficial 
Absorbents of the scrotum commonly enter into the upper ingui- 
nal glands, and thus unite to the great body of absorbents. 

The Absorbents of the Testicles, originate in the body, and the 
coats of the testicle, and in the epididymis, and are remarkably 
large and numerous. They proceed along the spermatic cord, 
through the abdominal ring, to the lumbar glands. These vessels 
are remarkable for the little communication they have with each 
other. 

The Deep-seated Absorbents of the Scrotum accompany the ab- 
sorbents of the testicle to the lumbar glands ; but those which 
are superficial enter the upper inguinal glands. 

The Absorbents of the Penis are also deep-seated and superfi- 
cial. The deep-seated arise from the body of the penis, and 
accompany the internal pudic artery into the pelvis. The super- 
ficial absorbents arise from the prepuce, and pass along the dor- 
sum of the penis. (See Fig. 73, p. 311.) There are frequently 
several trunks which receive branches from the lower surface of 
the penis in their course. At the root of the penis they gene- 
rally separate to the right and left, and pass to the glands on the 
respective sides. 



322 ABSORBENTS OF THE ABDOMEN AND THORAX. 

In females, the absorbents of the interior of the clitoris accom- 
pany the internal pudic artery. Some, which arise about the 
vagina, pass through the abdominal ring with the round liga- 
ment ; and others proceed to the inguinal glands. 

Of the Absorbents of the Abdomen and Thorax. 

The Absorbents of the lower portions of the parieles of the Ab- 
domen and Pelvis unite into trunks that follow the epigastric, the 
circumflex and the iliac, as well as the lumbar and sacral arteries, 
&c. They proceed to some of the glands which are in the 
groin ; or in the external iliac, the hypogastric, or some of the 
contiguous plexuses. 

The Absorbents of the Womb are extremely numerous ; and, in 
the gravid state, are very large. Those which are on the neck 
and anterior part of the body accompany the spermatic vessels. 

The Absorbents of the Bladder pass to small glands on its late- 
ral and inferior parts, and finally join the hypogastric plexus. 

The Absorbents of the Rectum are of considerable size. They 
pass through glands that lie upon that intestine, and unite with 
the lumbar plexus. 

The Absorbents of the Kidney are superficial and deep-seated. 
They are very numerous, but, in a healthy state of the parts, are 
discovered with difficulty. Cruikshank describes them as they 
appeared, filled with blood, in consequence of pressing upon the 
kidney when its veins were full of blood. Mascagni did not in- 
ject the superficial vessels with mercury ; but describes them as 
they appeared when filled with colourless size, after he had in- 
jected the blood-vessels of the organ with the coloured fluid. 
The deep-seated absorbents pass out of the fissure of the kidney 
with the blood-vessels, and unite with the superficial ; they pro- 
ceed to the lumbar plexus, and pass into different glands. 

Absorbent vessels can be proved to proceed from the pelvis of 
the kidney, and the ureters, by orifices analogous to those above 
mentioned. 

The Glandulce Renales are also supplied with absorbents, 
which are numerous in proportion to the size of the organs. 
They commonly join those of the kidney. 



ABSORBENTS OF THE INTESTINES.-MESENTERIO GLANDS. 323 

The Absorbents of the Intestines 

Have generally been called Lacteals, from the white colour of 
the chyle which they contain: but there seems no reason for be- 
lieving that they are different in their structure and nature from 
the absorbents in other parts of the body. A small number of 
them appear as if they formed a part of the structure of the in- 
testines, and originated from their external surface, as they do in 
other parts of the abdomen ; while the principal part of them are 
appropriated to the absorption of the contents of the cavity of the 
intestines. 

The first mentioned absorbents run between the muscular and 
peritoneal coats, and proceed for some distance lengthways on 
the intestine, while the others proceed for some distance within 
the muscular coat, with the arteries ; and, after passing through 
it, continue between the lamina of the mesentery. 

Branches of these different absorbents are frequently united in 
one trunk, so as to prove that there is no essential difference be- 
tween them. 

The absorbents which come from the internal surface of the 
intestines commence in the villi. The manner in which they 
originate has been the subject of considerable inquiry, as has 
been stated in the account of the intestines.* 

The lacteals or absorbents of the intestines are very numerous. 
They pass between the lamina of the mesentery to glands which 
are also seated between those lamina. The number of these 
glands is very considerable,! and they are various in size — 
some being very minute, and others eight or ten lines in diame- 
ter. They are generally placed at a small distance from each 
other, and are most numerous in that part of the mesentery 
which is nearest to the spine. They are almost always at some 
distance from the intestines. They appear to be precisely like the 
absorbent glands in other places. 

These absorbent vessels, in their course frequently divide into 
branches; which sometimes go to the same gland, sometimes to 
different glands, and sometimes unite with other absorbent ves- 

• See page 42. t They have been estimated between 130 and 150. 



324 ABSORBENTS OF THE STOMACH. 

sels. As they proceed, they frequently enlarge in size. When 
they have arrived near the spine, they frequently form three or 
four trunks, and sometimes one or two; which proceed in the 
course of the superior mesenteric artery, until they have arrived 
near to the aorta. Here they either pass into the thoracic duct, or 
descend and join the trunks from the inferior extremities, to 
form the thoracic duct. The absorbents of the great intestines 
are not equal in size to those of the small; but they are numer- 
ous. They enter into glands, which are very near, and in some 
places in contact with the intestine; and are commonly very 
small in size. The vessels which arise from the caecum, and the 
right portion, as well as the arch of the colon, unite with those 
of the small intestines ; while the vessels from the left side of 
the colon, and the rectum, proceed to the lumbar glands. 

The absorbents of the intestines are frequently injected with 
mercury ; but the injection does not proceed to their termination 
with so much facility as it does in other vessels of the same 
kind. They have, however, very often been seen in animals 
who were killed for the purpose after eating milk; and in several 
human subjects who died suddenly during digestion. The de- 
scription of the origin of the lacteals, quoted in page 45, from 
Mr. Cruikshank, was taken from a subject of this kind, of which 
an account is given in his work on the absorbent vessels, p. 59. 

It is worthy of note, that in several instances, in which the 
lacteals were thus found distended with chyle, the glands in the 
mesentery were also uniformly white. 

The Absorbents of the Stomach 

Are of considerable size, and form three divisions. The ves- 
sels of the first set appear upon both sides of the stomach, and 
pass through a few glands on the small curvature near the omen- 
tum minus. From these glands they proceed to others, which 
are larger, and which also receive some of the deep-seated ab- 
sorbents of the liver. The vessels from these glands pass to the 
thoracic duct, near the origin of the coeliac artery. The second 
arise also on both sides of the stomach, and pass to the left ex- 
tremity of the great curvature to unite with the absorbents of 



ABSORBENTS OF THE LIVER. jjgg 

that side of the great omentum. They then proceed to the lym- 
phatics of the spleen and pancreas, to the thoracic duct. The 
last set, pass off from the right extremity of the great curvature, 
and unite also with absorbents from the right portion of the 
omentum. They proceed near the pylorus, and go to the tho- 
racic duct, with some of the deep-seated absorbents of the liver. 
Although the absorbents of the stomach are deep-seated, as 
well as superficial, it is a general sentiment, that they do not con- 
tain chyle in the human subject; notwithstanding chyle has been 
found in the absorbents on the stomach of dogs, and some other 
animals. It ought, however, to be remembered, that Sabatier 
has, in some instances, seen white lines on the stomach, which 
he supposed to be lacteals. 

The Absorbents of the Liver 

Arc especially interesting, because they have been more com- 
pletely injected than those of any other viscus. They are deep- 
seated and superficial. The superficial, it has been already ob- 
served, admit of injection in a retrograde direction, and, there- 
fore can be exhibited most minutely ramified. They communi- 
cate freely with each other, and also with the deep-seated ves- 
sels, by their small ramifications ; so that the whole gland has 
been injected from one large vessel. 

The gland is so large, that the absorbents of the superior and 
inferior surfaces proceed from it in different directions. 

A large absorbent is generally found on the suspensory liga- 
ment. This is formed by the union of a great many branches that 
arise both on the right and left lobes, but principally on the right. 
It often passes through the diaphragm at an interstice which is 
anterior to the xiphoid cartilage, and then proceeds through 
the glands on the anterior part of the pericardium. 

Several absorbents proceed to the lateral ligaments on each 
side, and then pass through the diaphragm. Some of these 
branches return again into the abdomen, and the others generally 
run forwards in the course of the ribs, and join those which pass 
up from the suspensory ligament. The trunk, or trunks, formed 
by these vessels, either pass up between the lamina of the medi- 

vol. H. 28 



326 ABSORBENTS OF THE SPLEEN. 

astinum, and terminate in the upper part of the thoracic duct ; 
or they accompany the internal mammary arteries, and termi- 
nate on the left side in the thoracic duct, and on the right in the 
trunk of the absorbents of that side. 

The Absorbents on the concave side of the liver are as numer- 
ous as those on the convex side ; they are also very abundant 
on the surface of the gall-bladder. The greatest part of them 
join the deep-seated vessels. 

The Deep-seated Absorbents proceed in considerable numbers 
from the interior of the liver through the portae. They accom- 
pany the biliary ducts and the great blood-vessels of the organ; 
and, after passing through several glands, near the vena porta- 
rum, terminate in the thoracic duct, near the commencement 
of the superior mesenteric artery. 

Mascagni states, that the absorbents of the liver will be dis- 
tended, by injecting warm water into the biliary ducts, or the 
vena portarum. 

He also observes, that in those preparations in which the su- 
perficial vessels are completely injected, in the retrograde direc- 
tion, the peritoneal coat of the liver appears to be composed en- 
tirely of absorbent vessels; and to be connected to the mem- 
brane within, by many filaments, which are also absorbent ves- 
sels. 

The Absorbents of the Spleen 

Are composed of superficial and deep-seated vessels; but they 
differ greatly from those of the liver, in this respect, that the su- 
perficial vessels are remarkably small in the human subject. 

Mascagni, however, asserts, that when the blood-vessels of the 
spleen are injected with size, coloured with vermilion, these ab- 
sorbents will be filled with colourless size. 

In the spleen of the calf the superficial absorbents, are re- 
markably large. 

In the human subject the superficial absorbents of the spleen 
proceed from the convex to the concave surface, and there 
communicate with the deep-seated absorbents, which proceed 
from the interior of the organ with the blood-vessels. 



ABSORBENTS OF THE PANCREAS. 327 

These Deep-seated Absorbents are very numerous, and also 
large. They accompany the splenic artery; and in their course 
pass through many glands, some of which are said to be of a 
dark colour. The glands lie on the splenic artery, at a short 
distance from each other. The absorbents of the spleen receive 
the absorbents of the pancreas in their course; they unite with 
the absorbents of the stomach and the lower surface of the liver, 
and pass with them to the thoracic duct. 

Little has been latterly said by practical anatomists respecting 

The Absorbents of the Pancreas. 

Mr. Cruikshank once injected them in the retrograde direction; 
he found that they came out of the lobes of the pancreas in short 
branches like the blood-vessels, and passed at right angles into 
the absorbents of the spleen, as they accompanied the artery in 
the groove of the pancreas. 

The Thoracic Duct* 

Or common trunk of the absorbent system, is formed by the 
union of those absorbent vessels which are collected on the 
lumbar vertebrae. 

These vessels, as it has been already observed, are derived 
from various sources, viz. 

The lower extremities ; the lower part of the trunk of the 
body ; the organs of generation ; the intestines, with the other 
viscera of the abdomen and pelvis, except a part of the liver. 
Their number is proportioned to the extent of their origin: for, 
with the numerous glands appropriated to them, they form the 
largest absorbent plexus in the body, and are spread over a con- 
siderable portion of the aorta and the vena cava. 

The manner in which these vessels unite to form the thoracic 
duct, is very different in different subjects ; but in a majority of 
cases it originates immediately from three vessels, two of which 
are the trunks of the absorbents of the lower extremities, and 

* First discovered by Eustachius, in the horse, 15G4; but he considered it a vein 
for the nourishment of the thoracic viscera. — h. 



328 THORACIC DUCT. 

the other is the common trunk of the lacteals and the other ab- 
sorbents of the intestines. , 

These vessels generally unite on the second or third lumbar 
vertebras ; and, in some instances, the trunk which they form 
dilates considerably, soon after its commencement; in conse- 
quence of which it was formerly called the receptacle of the chyle. 
At first it lies behind the aorta, but it soon inclines to the right of 
it, so as to be behind the right crus of the diaphragm. In the 
thorax, it appears on the front of the spine, between the aorta 
and the vena azygos, and continues between these vessels until 
it has arrived at the fourth or third dorsal vertebra. It then 
inclines to the left, and proceeds in that direction until it emerges 
from the thorax, and has arisen above the left pleura, when it 
continues to ascend behind the internal jugular, nearly as high 
as the sixth cervical vertebra : it then turns downward and for- 
ward, and after descending from six to ten lines, terminates in 
the back part of the angle formed by the union of the left internal 
jugular with the left subclavian vein. Sometimes, after rising 
out of the thorax, it divides into two branches, which unite 
before they terminate. Sometimes it divides, and one of the 
branches terminates at the above mentioned angle, and the other 
in the subclavian vein, to the left of it. 

The orifice of the thoracic duct has two valves, which effec- 
tually prevent the passage of blood into it from the vena cava. 

There are sometimes slight flexures in the course of the duct: 
but it generally inclines to the left, in the upper part of the 
thorax, as above mentioned ; and is then so near the left lamen 
of the mediastinum that, if it be filled with coloured injection, it 
can be seen through that membrane, when the left lung is raised 
up and pressed to the right. 

The duct sometimes varies considerably in its diameter in 
different parts of its course. About the middle of the thorax it 
has often been found very small. In these cases it generally 
enlarges in its progress upwards, and is often three lines in dia- 
meter, in its upper part. Many anatomists have observed it to 
divide and to unite again, about the middle of the thorax. 



ABSORBENTS OF THE LUNGS 329 

The Absorbents of the Lungs. 

The absorbents of the lungs are very numerous, and, like those 
of other viscera, are superficial and deep-seated. 

The large superficial vessels run in the interstices between the 
lobuli, and, therefore, form angular figures of considerable size- 
In successful injections, the vacancies within these figures are 
filled up with small vessels, and the whole surface appears 
minutely injected. 

Mascagni observes, that the superficial vessels are very visible 
when any fluid has been effused into the cavity of the thorax ; 
or when warm water is injected, either into the blood-vessels of 
the lungs, or the ramifications of the trachea. Cruikshank de- 
monstrated them by inflating the lungs of a still-born child ; in 
which case the air passes rapidly into them. 

The deep-seated absorbents accompany the blood-vessels and 
the ramifications of the bronchia?. They pass to the dark-co- 
loured glands, which are situated on the trachea at its bifurcation; 
and on those portions of the bronchia? which are exterior to the 
lungs. The injection of the absorbents, which pass to and from 
these glands, seem to prove that they are of the same nature 
with the absorbent glands in general, notwithstanding their colour. 
They are numerous; and they vary in size, from a diameter of 
two lines to that of eight or ten. 

From these glands, some of the absorbents of the left lung pass 
into the thoracic duct, while it is in the thorax, behind the bifur- 
cation of the trachea ; others proceed upwards and enter into it 
near its termination ; while those of the right lung terminate in 
the common trunk of the absorbents of the right side. 



28* 



330 ABSORBENTS OF THE HEAD AND NECK. 



CHAPTER XL 

OF THE ABSORBENTS OF THE HEAD AND NECK; OF THE UPPER 
EXTREMITIES, AND THE UPPER PART OF THE TRUNK OF THE 
BODY. 

The absorbents from the various parts of the head pass through 
glands, which are situated on the neck or the lower part of the 
head. Those on the head are the least numerous, and also the 
least in size. Some of them, which are generally small, lie 
about the parotid gland. Several of them, which are also small, 
are on the occiput, below and behind the mastoid process. Some- 
times there are two or three on the cheek, near the basis of the 
lower jaw, about the anterior edge of the masseter muscle. 
Below the lower jaw, in contact with the sub-maxillary gland 
and anterior to it, there are always a number of these glands, 
which are generally small, but often swelled during infancy. 

The Glands on the Neck are the most numerous. Many of 
them are within the sterno-mastoid muscle, and accompany the 
internal jugular vein and the carotid artery down to the first rib. 
Many also lie in the triangular space between the sterno-mastoid 
muscle, the trapezius, and the clavicle; therefore it has been truly 
said that the glands of the neck are more numerous than those 
of any other part except the mesentery. They are frequently 
called Glandules Concatenates. It has already been mentioned 
that the various absorbents, which are connected with these 
glands, unite on each side into a trunk, which on the left passes 
into the thoracic duct, and on the right into the common trunk 
of the absorbents of that side. 

Of the Absorbents of the Head and Neck. 

There is the greatest reason to believe that the brain and its 
appendages are supplied with absorbents like the other parts. 
Some of these vessels have been discovered in the cavitv of the 



ABSORBENTS OF THE UPPER PART OF THE TRUNK. 33^ 

cranium ; but very little precise information has as yet been ob- 
tained, respecting the extent, or arrangement of the absorbent 
system, in this part of the body. 

The absorbents on the exterior of the head are as numerous 
as in other parts of the body. On the occiput they pass down, 
inclining towards the ear, and continue behind it to the side of 
the neck ; behind the ear they pass through several glands. 
From the middle or temporal region of the cranium, they pass 
with the carotid artery before the ear, and enter some small 
glands that lie on the parotid ; from which they continue to the 
neck. 

They are on every part of the face, and unite, so that their 
principal trunks, which are very numerous, pass over the basis 
of the lower jaw, near the facial artery. They enter into glands, 
which are also very numerous, immediately under the jaw, or 
which are sometimes to be found on the cheek, at the anterior 
edge of the masseter muscle. All the absorbents of the exterior 
part of the head pass to the glands on the side of the neck, al- 
ready described. 

Those from the interior of the nose accompany the ramifica- 
tions of the internal maxillary artery, and proceed to glands be- 
hind the angle of the lower jaw ; into which glands also enter 
the absorbents of the tongue and inner parts of the mouth. 

The absorbents of the thyroid gland, on the left side, pass 
down to the thoracic duct ; those on the right, unite to the trunk 
of the absorbents on that side, near its termination. It has been 
remarked, that they can be readily injected, by thrusting the pipe 
into the substance of the gland. 

Of the Absorbents of the Arm and Upper Part of the Trunk. 

The absorbents of the arm are superficial and deep-seated, 
like those of the lower extremity. 

The superficial absorbents have been injected on the anterior 
and posterior surfaces of the fingers and the thumb, near their 
sides. On the back of the hand they are very numerous, and 
increase considerably in their progress up the fore-arm. As 
they proceed upwards, they incline towards the anterior surface 
of the fore-arm ; so that by the time they have arrived at the 



332 ABSORBENTS OF THE ABM AND UPrER PART OF THE TRUNK- 

elbow, almost all of them are on the anterior surface. The ab- 
sorbents on the anterior part of the hand are not so numerous 
as those on the back. Sometimes there are digital branches 
from the fingers, and an arcus in the palm ; but this bow is not 
formed by one large absorbent, analogous to the ulnar artery. 
On the contrary, its two extremities are continued over the wrist, 
and pass on the fore-arm like the absorbents. 

At the elbow some of them often pass into one or two small 
glands, which are very superficial ; but the whole of the absorb- 
ents, somewhat reduced in number, as some of them unite to- 
gether, pass along with the blood-vessels into the hollow of the 
arm-pit, where they enter the axillary glands. There are gene- 
rally one or more vessels which pass in the course of the cephalic 
vein, between the pectoral and the deltoid muscle, and enter into 
some of the glands under the clavicle. 

There are almost always several glands in and near the axilla. 
Some of them are very near the great blood-vessels ; sometimes 
one or more of them are much lower ; sometimes they are to be 
found under the pectoral muscle. They are commonly not so 
large as those of the groin, and are surrounded with fat. 

The deep-seated absorbents originate also at the fingers, and 
soon accompany the branches of the arteries. Those which 
attend the radial artery, originate on the back of the hand, and 
also in the palm, where they are associated with the arcus pro- 
fundus. They go up with the radial artery to the elbow, and 
sometimes pass through a small gland about the middle of the 
fore-arm. 

, Those which attend the ulnar artery, commence under the 
aponeurosis palmaris, and go with the artery to the elbow ; at 
the bend of the elbow they are generally joined by one or more, 
which accompany the interosseal artery; there they unite, so as 
to form several trunks, which pass up to the axilla with the hu- 
meral artery. They sometimes pass through one or two glands, 
which are near the elbow; and they receive in their course, 
deep-seated branches from the muscles on the humerus. 

The absorbents from the anterior and external part of the 
thorax, and the upper part of the abdomen, also proceed to the 



RIGHT BRACHIOCEPHALIC TRUNK. 333 

axilla, and enter into the glands there ; those which are deep- 
seated joining the deep-seated vessels. The absorbents of the 
mammas pass to the same glands; and when they are affected 
with the virus of cancer, can often be perceived, in their course, 
in the living subject. 

The absorbents of the uppermost half of the back, and those 
of the back of the neck, go likewise to the axilla. 

The absorbent vessels, collected from these various sources, 
proceed from the exterior to the innermost glands, but with a 
considerable diminution of their number: they accompany the 
subclavian vein, and are reduced to one or two trunks, that gene- 
rally unite before their termination. On the leftside, the absorb- 
ents of the head and neck generally open into the thoracic duct, 
as has been already observed ; and those of the left arm also 
open into the thoracic duct, or into the subclavian vein very near 
it. On the right side the absorbents from each of these parts 
empty into the common trunk, which often is formed by the union 
of large vessels, from four sources, and called brachio-cephalic ; 
namely, the head, the thyroid gland, the right arm, and the right 
cavity of the thorax, &c. The diameter of the trunk is very con- 
siderable ; but it is often not more than half an inch in length. 
It generally opens into the right subclavian vein, at the place 
where it unites to the right internal jugular. 

Two respectable physiologists of Europe, (M. Seguin, of Paris, and the late 
Dr. Currie of Liverpool,) have doubted whether absorption takes place on 
the external surface of the skin.* This question has been examined in a 
very interesting manner by several graduates of the University of Penn- 
sylvania, who chose it for the subject of their inaugural theses; namely, 
Drs. Rousseau, Klapp, Daingerfield, Mussey, and J. Bradner Stewart. 

The three first of these gentlemen state that when spirit of turpentine, and 
several other substances which are commonly supposed to be absorbed by 
the skin, were applied to it in a way which prevented their volatile parts 

* I believe that M. Seguin's Memoir on this subject was read to the Academy 
of Sciences a short time before the meetings of that body were suspended. It 
was published by M. Fourcroy, in La Medicine Eclairee par les Sciences Phy- 
siques, vol. iii. An extract from M. Fourcroy's publication may be seen in the 19th 
chapter of the first volume of Dr. Currie's " Medical Reports on the Effects of 
Water," &.c. in which is also contained a statement of the Doctor's own experi. 
ments and reflections. 



334 FACTS RELATING TO CUTANEOUS ABSORPTION. 

from entering the lungs by respiration, no absorption took place. But 
when the inspired air was impregnated with exhalations from these sub- 
stances, they perceived satisfactory proofs that the exhalations entered the 
system. From these facts they inferred that when those articles entered 
the body by absorption, they were taken in by the lungs, and not by the 
external surface. 

On the other hand, the two gentlemen last mentioned, state that after im- 
mersing themselves in a bath consisting of a decoction of rhubarb, of 
madder, or of turmeric, their urine became tinged with these substances. 
They also assert that the colouring matter of these different articles is not 
volatile ; and, therefore, could not have entered the lungs during the ex- 
periments.* 

The statement in page 304, from Dr. Sommering, that when mercury is in- 
jected backwards in the absorbent vessels which originate on the foot, it 
will sometimes appear in small globules on the skin of the foot, has an im- 
portant connexion with this subject, f 



About the middle of the last century, it was generally believed by anatomists 
that absorption was performed by the veins. This doctrine seemed to be 
established by the experiments of Kaaw Boerhaave, which are related with 
many other interesting statements, in his work, entitled " Perspiratio 
Dicta Hippocrati," &c. published at Leyden, in 1738. In these experi- 
ments it appeared to the author, that when the stomach of a dog was 
emptied of its contents, and filled with warm water, immediately after 
death, the water passed into the minute ramifications of the veins of the 
stomach, and from them to the vena portarum, and ultimately to the heart 
in large quantities. 

This account appears to be disproved by some experiments of the late John 
Hunter, made about twenty years after, and published in the Medical 
Commentaries of Dr. William Hunter, part I. — Mr. Hunter's experi- 
ments have been considered as establishing the fact, that absorption, (in 
the intestines at least,) is performed exclusively by the lacteals, or proper 
absorbent vessels, and not at all by the veins. Kaaw Boerhaave is of 

* The Thesis of Dr. Rousseau was published in 1800. Those of Drs. Klapp 
and Daingerfield in 1805. Dr. Mussey published in the Third Supplement to the 
Medical and Physical Journal of Dr. Barton, in 1809. Dr. Stewart published in 
1810. Additional Observations by Drs. Klapp, Rousseau and Smith, are published 
in the Philadelphia Medical Museum, vol. i. new series. 

t Since the publication of the first volume, the author has enjoyed the advantage 
of consulting a translation, in manuscript, of some parts of the German edition of 
Dr. Sommering's valuable work on the Structure of the Human Body. 



EXPERIMENTS OP BOERHAAVE AND HUNTER. 335 

course supposed to have been mistaken ; and Mascagni, who has repeated 
his experiments, refers the appearance of water in the veins to transu- 
dations through the coats of the intestines ; which he has observed to 
take place in a great degree. 

In the year 1809, a memoir was presented to the national institute of France 
by Messrs. Magendie and Delile, which contains an account of some ex- 
periments that have an important relation to the above mentioned sub- 
jects—The authors being greatly surprised at the rapidity with which the 
poison of Java, &c. appeared to enter the sanguiferous system, instituted 
a series of experiments to determine whether these substances proceeded 
to that system by the circuitous route of the absorbent vessels, or by the 
shorter course of the veins. Two of their experiments are especially 
interesting. They made an incision through the parietes of the abdomen 
of a living dog, who had eaten a large quantity of meat some hours before, 
(that his lacteals might be visible from their distention with chyle,) and 
drawing out a portion of the small intestine, they applied two ligatures to 
it, at the distance of five inches from each other. The portion of intestine 
between these ligatures was then separated by incision from the rest of 
the intestinal tube, and all the lacteals and blood-vessels, &c. which passed 
to and from it, were divided, except one artery and a vein. A considerable 
length of this artery and vein were detached from all the surrounding 
parts, so that the authors supposed these vessels to form the only connexion 
between the portion of the intestine, and the rest of the body. Into the 
cavity of the intestine, which was thus circumstanced, they introduced a 
small quantity of the poison, and, to their astonishment, it produced its 
fatal effects in the same manner it would have done if it had been in- 
troduced into the intestine while all its connexions with the body were 
entire. This experiment, they assert, was repeated several times, without 
any difference in the result. 

After several other experiments, they finally separated the thigh from the 
body of a living dog in such a manner that the crural artery and vein 
were left undivided. A quill was then introduced into the artery, and two 
ligatures were applied to fix it round the quill. The artery was then 
divided between the two ligatures. The vein was managed in the same 
manner. There was, therefore, no communication between the limb and 
the body, except by the blood which passed through the divided vessels 
and the quills. The poison was then introduced under the skin of the 
foot, and soon occasioned the death of the animal ; its deleterious effects 
commencing about four minutes after its application to the foot. This 

* Tbe title of the paper is a " Memoir on the Organs of Absorption in Mammi- 
ferous Animals." A translation of it was published in the Medical and Philo- 
sophical Register of New York, and in several other periodical works. 



336 EXPERIMENTS OF MAGENDIE AND DELILE. 

experiment appears to prove decidedly that the blood is the vehicle by 
which poison, when applied to the extremities, is carried to the body ; 
although it may not determine the question whether this poison was taken 
up by the absorbents or by the veins.* 

Some other experiments made by the authors gave results, which are very 
difficult indeed to explain. They wished to know if the blood of an animal 
thus contaminated, would produce similar effects upon another animal ; 
and, with a view to ascertain this point, they insinuated a small piece of 
wood, covered with the poison, into the thick part of the left side of the 
nose of a dog. Three minutes after the introduction of the poison, they 
transfused blood from the jugular vein of the same side, into one of the 
veins of another dog. About one minute after the commencement of the 
transfusion, the effects of the poison began in the dog to which it was ap- 
plied, and continued until his death. Transfusion into the veins of the 
other dog went on during the whole time, and he received a large quantity 
of blood from the dying dog, without producing any effect. They varied 
this experiment in the following manner. The thigh of a dog was sepa- 
rated from the body; the artery and the vein were arranged as in the former 
experiment; and poison was introduced into the foot. Three minutes 
after the introduction of the poison the blood of the crural vein was passed 
into the jugular vein of another animal and transfusion was continued five 
minutes without producing any effect upon the animal receiving the blood ; 
it was then stopped, and the crural vein was so arranged that the blood 
flowed from it into the animal to which it belonged. This animal very 
soon exhibited symptoms of the operation of the poison. f 

From these very interesting experiments the authors infer that "foreign 
matters do not always proceed through the Lymphatic or Absorbent Ves- 
sels, when they enter into the Sanguiferous system." 

* This experiment has been repeated in Philadelphia. See Professor Chapman's 
Medical and Physical Journal for February, 1823, No. 10. — h. 

t An account of these experiments was published by M. Magendie in a pamphlet. 
A statement of them is also contained in the report made to the Institute by the 
committee to whom the memoir was referred, which is published in the Journal 
de Physique, for March, 1813. In that statement this last mentioned experiment 
is omitted. 

A most interesting series of inquiries and experiments in regard to the laws of 
absorption will be found in Professor Chapman's Journal of the Medical and Phy- 
sical Sciences, No. 6, in a report of a Committee of the Academy of Medicine, 
signed by Doctors Lawrence and Coates, of this city. And a continuation of the 
same will be found in No. 10 of the same Journal, signed by Doctors Lawrence 
and Coates. Since the publication of the latter, to the regret of all who knew him, 
and to the great loss of Anatomy and of Physiology, the indefatigable and excel- 
lent Lawrence is no more. — h. 



OF THE ABSORBENT VESSELS. 337 

This memoir was referred by the Institute to four of its members, who 
are particularly distinguished by their profound knowledge of anatomy 
and physiology. These gentlemen, after stating their belief that the 
functions of the lymphatic or absorbent system have been completely as- 
certained by the experiments and observations of Hunter, Cruikshank, 
Mascagni, &c. say farther, that in their opinion, the above mentioned in- 
ference ought to be a little modified, and that facts are not sufficiently nu- 
merous, or applicable to the point in question, to justify the inference that 
foreign matters do not always proceed through the Lymphatic or Absorb- 
ent Vessels, when they enter the Sanguiferous system. But they also add, 
that as the author is still engaged in a series of experiments on the subject, 
they will suspend their judgment respecting the inferences to be deduced 
from the present statement. 

The most extensive account of the absorbent system is contained in the 
" Historia et Ichnographia Vasorum Lymphaticorum Corporis Humani" of 
Mascagni, — " The Anatomy of the Absorbing Vessels of the Human Body, 
by W. Cruikshank ;" — and " The Description of the Lymphatic System, 
by William Hewson," (the second volume of his Experimental Inquiries,) 
are also very interesting publications. 

vol. II. 29 



338 



EXPLANATION OF PLATE IX. 



Fig. 1. Exhibits the more superficial Lymphatic Vessels of the Lower Ex- 
tremity. 

A, The spine of the os ilium. B, The os pubis, c, The iliac artery. D, 
The Knee. E, E, F, Branches of the crural artery. G, The musculus 
gastrocnemius. H, The tibia. I, The tendon of the musculus tibialis anticus. 
On the outlines, a, A lymphatic vessel belonging to the top of the foot, b, 
Its first division into branches, c, c, c, Other divisions of the same lymphatic 
vessel, d, A small lymphatic gland, e, The lymphatic vessels which lie 
between the skin and the muscles of the thigh, f f, Two lymphatic glands 
at the upper part of the thigh, below the groin, g g, Other glands, h, A 
lymphatic vessel which passes by the side of those glands without communi- 
cating with them, and bending towards the inside of the groin at (i), opens 
into the lympatic gland (k). 11, Lymphatic glands in the groin, which are 
common to the lymphatic vessels of the genitals and those of the lower ex- 
tremity, m, n. A plexus of lymphatic vessels passing on the inside of the 
iliac artery. 

Fig. 2. Exhibits a back view of the Lower Extremity, dissected so as to 
show the deeper seated Lymphatic Vessels which accompany the Ar- 
teries. 

A, The os pubis. B, The tuberosity of the ischium. C, That part of the 
os ilium which was articulated with the os sacrum. D, The extremity of 
the iliac artery appearing above the groin. E, The knee. F F, The two 
cut surfaces of the triceps muscle, which was divided to show the lymphatic 
vessels that pass through its perforation along with the crural artery. G, 
The edge of the musculus gracilis. H, The gastrocnemius and soleus 
much shrunk by being dried, and by the soleus being separated from the 
tibia to expose the vessels. I, The heel. K, The sole of the foot. L. The 
superficial lymphatic vessels passing over the knee, to get to the thigh. On 
the outlines: M, the posterior tibial artery, a, A lymphatic vessel accom- 
panying the posterior tibial artery, b, The same vessel crossing the artery, 
c, A small lymphatic gland, through which this deep-seated lymphatic vessel 
passes, d, The lymphatic vessel passing under a small part of the soleus, 
which is left attached to the bone, the rest being removed, e, The lymphatic 
vessel crossing the popliteal artery, f, g, h, Lymphatic glands in the ham, 
through which the lymphatic vessel passes, i, The lymphatic vessel passing 
with the crural artery, through the perforation of the triceps muscle, k, The 
lymphatic vessel, after it has passed the perforation of the triceps, dividing 
into branches, which embrace the artery (1). m, A lymphatic gland be- 
longing to the deep-seated lymphatic vessel. At this place those vessels 
pass to the fore part of the groin, where they communicate witli the super- 
ficial lymphatic vessel, n, Apart of the superficial lymphatic vessel appearing 
on the brim of the pelvis. 



EXPLANATION OF PLATE IX 339 

Fig. 3. Exhibits the Trunk of the Human Subject prepared to show the 
Lymphatic Vessels and the Ductus Thoracicus. 

A, The neck. B B, The two jugular veins. C, The vena cava superior. 
D D D D, The subclavian veins. E, The beginning of the aorta, pulled to the 
left side by means of a ligature, in order to show the thoracic duct behind it. 
F, The branches arising from the curvature of the aorta. G G, The two 
carotid arteries. H H, The first ribs. 1 1, The trachea. K K, The spine. 
L L, The vena azygos. M M, The descending aorta. N, The coeliac artery, 
dividing into three branches. O, The superior mesenteric artery. P, The 
right crus diaphragmatis. Q Q, The two kidneys. R, The right emulsrent 
artery. S S, The external iliac arteries, g, d, The psoas muscles. T, The 
internal iliac artery. U, The cavity of the pelvis. XX, The spine of the 
os ilium. Y Y, The groins, a, A lymphatic gland in the groin, into which 
lymphatic vessels from the lower extremity are seen to enter, b b, The 
lymphatic vessels of the lower extremities passing under Poupart's ligament, 
cc, A plexus of the lymphatic vessels lying on each side of the vessel, d, 
The psoas muscle with lymphatic vessels lying upon its inside, e, A plexus 
of the lymphatics, which have passed over the brim of the pelvis at (c), 
having entered the cavity of the pelvis, and received the lymphatic vessels 
belonging to the viscera contained in that cavity, next ascends and passes 
behind the iliac artery to (g). f, Some lymphatic vessels of the left side 
passing over the upper part of the os sacrum, to meet those of the right side, 
g, The right psoas, with a large plexus of lymphatics lying on its inside. 
hh, The plexus lying on each side of the spine, ii i, Spaces occupied by 
the lymphatic glands, k, The trunk of the lactfcals lying on the under side 
of the superior mesenteric artery. 1, The same dividing into two branches, 
one of which passes on each side of the aorta: that of the right side being 
seen to enter the thoracic duct at (m). m, The thoracic duct, beginning 
from the large lymphatics, n, The duct passing under the lower part of the 
crus diaphragmatis, and under the right emulgent artery, o, The thoracic 
duct penetrating the thorax, p, Some lymphatic vessels joining that duct 
in the thorax, q, The thoracic duct passing under the curvature of the 
aorta to get to the left subclavian vein — the aorta being drawn aside to show 
the duct. ?-, A plexus of lymphatic vessels passing upon the trachea from 
the thyroid gland to the thoracic duct. 



PART X. 



OP THE BRAIN AND SPINAL MARROW: OF THE EYE AND 

THE EAR. 

CHAPTER XII. 

OF THE BRAIN. 

The whole of the soft mass, which fills the cavity of the 
cranium, is called the brain. This mass is covered by three 
membranes : two of which were called meninges or matres, by 
the ancient anatomists: who believed that all the other mem- 
branes of the body originated from them. 

These membranes are denominated the Dura Mater, Tunica 
Arachnoidea, and Pia Mater. 

Of the Membranes of the Brain, and Sinuses of the Dura Mater. 

The Dura Mater encloses the brain and all its appendages, 
and lines the different parts of the cranium. It consists of one 
membrane of a very dense texture, which in several places is 
composed of two or more lamina. It is the thickest and strongest 
membrane of the body, and is composed of tendinous fibres, 
which have a shining appearance, particularly on its inner sur- 
face. In many parts these fibres run in a variety of directions, 
and decussate each other at different angles. 

The dura mater adheres every where to the surface of the 
cranium, in the same manner as the periosteum adheres to the 
bones in the other parts of the body; but is more firmly con- 
nected at the sutures and foramina than elsewhere; and so much 
more firmly in children than in adults, that in separating it from 



DURA MATER.-TL'NICA ARACHNOIDEA. 34 \ 

the cranium, it is apt to bring along with it some of the fibres of 
the bone to which it is attached. In the adult, the separation of 
the bone from the membrane is less difficult, in consequence of 
many of the fibres being obliterated ; although in old age the 
adhesion is sometimes very strong. 

The inner surface of the dura mater, which is remarkably 
smooth, is in close contact with the brain, but adheres only where 
the veins go into the sinuses ; and is lubricated by a fluid dis- 
charged through its vessels, which guards the brain from danger, 
according as it may be affected by the different states of respi- 
ration. 

The dura mater serves as a defence to the brain, and supplies 
the place of a periosteum to the inside of the cranium ; giving 
nourishment to it, as is evident from the numerous drops of blood 
which appear after removing a portion of it. 

The proper blood-vessels of the dura mater are not very nu- 
merous. Its arteries are derived partly from the external carotids, 
and partly from the internal carotids and the vertebral arteries. 
Corresponding veins accompany these arteries; but the dura 
mater forms also reservoirs, that contain the venous blood, which 
is brought from the substance of the brain. These are called 
sinuses, and are very different from common veins. 

Nerves have been traced into the dura mater by the French 
anatomists, derived from the sympathetic in the neck. There 
have been disputes respecting its sensibility ; but there is reason 
to believe that in a sound stale it has very little. 

The Tunica Arachnoidea is an exceedingly thin, tender, and 
transparent membrane, in which no vessels have been hitherto 
observed. 

It is spread uniformly over the surface of the brain, enclosing 
all its convolutions, without insinuating itself between any of 
them. 

At the upper part of the brain it adheres so closely to the 
subjacent coat by fine cellular substance, that it can scarcely be 
separated from it; but in different parts of the base of the brain, 
particularly about the tuber annulare and medulla oblongata, it 

20* 



342 PIA MATER 

is merely in contact with the membrane under it, and may readily 
be raised from it by the assistance of the blow-pipe. 

The Pia Mater, named from its tenderness, is somewhat of the 
nature of the former covering, but is extremely vascular. 

It covers the brain in general, enters double between all its 
convolutions, and lines the different cavities called ventricles. 

It serves to conduct and support the vessels of the brain, and 
allows them to divide into such minute parts, as to prevent the 
blood from entering the tender substance of this viscus with too 
great force. 

The arteries of the pia mater are the same with those of the 
brain, and are derived from the internal carotids and vertebrals. 

The veins differ in no respect from those of the other viscera, 
excepting in this, that they do not accompany the arteries. 

From the dura mater certain membranous processes go off, 
forming incomplete partitions, which partially divide the cavity 
of the cranium ; and in the same partial manner, separate the 
parts of the brain from each other : thus preventing them from 
pressing upon each other, and keeping them steady. 

They are formed of the internal lamina or layer of the dura 
mater, like a plait, and therefore each of them consists of a double 
membrane. 

The most conspicuous of these is denominated the falx, which 
extends from the anterior to the posterior part of the cranium, 
and divides the upper part of the brain into two hemispheres : 
but it is not sufficiently deep to divide the whole of the brain ; 
for, between the under edge of it, and the base of the cranium, 
there is a large space occupied by a portion of the brain, which 
is undivided : and, therefore, common to both hemispheres. 

The falx begins at the middle of the sphenoid bone, and, con- 
tinuing its origin from the crista galli of the ethmoid bone, runs 
along the upper and middle part of the head ; adhering first to 
the frontal, then to the joining of the parietal, and afterwards to 
the middle of the occipital bone. 

In its passage it becomes gradually broader, and terminates 
behind, in the middle of the tentorium. 

It runs from before backwards in a straight direction, and has 



FALX MAJOR.-TENTORIUM.-FALX MINOR 343 

some resemblance in shape to a sickle or sithe, placed with its 
edge downwards ; from which circumstance it has obtained the 
name of falx. 

After extending backwards as far as the centre of the crucial 
ridge, on the internal surface of the occipital bone, it extends to 
each side, and forms a horizontal partition, which partially di- 
vides the lower part of the cavity from the upper : but it does 
not extend so far forward, as to separate, completely, the mass 
which is under it, or the cerebellum, from the upper part of the 
brain, or cerebrum. 

This horizontal membrane is called the tentorium and also the 
transverse septum : it is connected behind to the inner transverse 
ridges and grooves of the occipital bone, and, at the fore and 
outer edges, to the ridges and great angles of the temporal bones, 
and terminates at the posterior clinoid process of the sphenoid 
bone. 

Between the inner edge of the tentorium and the posterior 
clinoid process of the sphenoid bone, there is a large notch, or 
foramen ovale, where the brain and cerebellum are united, or 
where the tuber annulare is chiefly situated. 

The tentorium keeps the falx tense, and forms a floor or vault 
over the cerebellum, which prevents the cerebrum from pressing 
upon it. 

The falx minor, or septum cerebelli, is placed between the 
lobes of the cerebellum. It descends from the under and back 
part of the falx in the middle of the tentorium, adheres to the 
inferior longitudinal spine of the os occipitis, and terminates in- 
sensibly at the edge of the foramen magnum of that bone. 

Besides the process of the dura mater already described, there 
are four of inferior consideration ; two of which are situated at 
the sides of the sella turcica, and two at the edges of the fora- 
mina lacera. 

As these partitions arise like plaits from the internal surface of 
the dura mater, there must necessarily be a cavity, larger or 
smaller, between the external layer of the dura mater, which 
lines the internal surface of the cranium, and the basis of the 
partition which arises from it: this cavity must continue along 



344 sinuses. 

the whole basis of the partition, and a section of it will Le trian- 
gular. 

This cavity is of considerable size at the upper edge of the 
falx, where it rises from the dura mater, and also where it forms 
the tentorium ; and at the posterior edges of the tentorium, where 
it adheres to the occipital bone. 

The cavity at the upper edge of the falx is called the longitudi- 
nal sinus ; that at the posterior edge of the tentorium forms two 
cavities, called the transverse sinuses ; and that which is at the 
junction of the falx and tentorium has the name of the torcular, 
or press of Herophilus. 

The veins of the brain open into these sinuses ; and the blood 
flows through them into the internal jugular veins. They differ 
from veins principally in this : that they are triangular, and, by 
the tension of the dura mater, are protected from pressure. 

The principal sinuses are, 

1. The longitudinal sinus, which begins at the crista galli, and, 
running along the upper edge of the falx until it arises at the ten- 
torium, increases gradually in size, and terminates in the two 
lateral sinuses. [Io this sinus, and beneath the dura mater near 
the top of the head, are many small bodies of various sizes called 
glandulse Pacchioni. They are of various dimensions, from a 
line and less to three or four lines in diameter. One of the largest 
of these glands on each side protrudes through the dura mater 
from the surface of the brain, and makes a pit in the os parietale. 
Vesalius demonstrated these bodies in 1543. Pacchioni also 
demonstrated them fifty years afterwards; and, claiming them 
as a discovery of his own, succeeded in attaching his name to 
them.] 

2. The two lateral sinuses run in depressions of the occipital 
and temporal bones, until they terminate in the internal jugular 
veins at the foramen lacerum. 

3. The torcular Herophili, which receives a large vein from 
the interior of the brain, and is situated at the junction of the falx 
and tentorium, opening into the longitudinal sinus, where it di- 
vides into the lateral sinuses. 



CEBEBRUM. 345 

These are the largest sinuses of the dura mater ; but, in addi- 
tion to these, there are several small sinuses : as, 

4. The inferior longitudinal sinus, which is situated at the 
under edge of the falx, and receives blood from the central parts 
of the cerebrum ; it terminates in the torcular Herophili, near 
the beginning. The other small sinuses are situated under the 
brain ; viz. 

5. The circular sinus of Ridley,* which frequently surrounds 
the pituitary gland, and carries the blood from the contiguous 
parts to the 

6. Cavernous sinuses, which are placed at the sides of the sella 
turcica, surrounding the carotid arteries and the sixth pair of 
nerves, and receive blood from the circular sinuses and several 
contiguous parts, and discharge it into the 

7. Inferior petrous sinuses, which are placed at the bases of 
the partes petrosae, and discharge this blood into the ends of the 
lateral sinuses. To these should be added 

8. The superior petrous sinuses, which are situated on the 
upper edges of the petrous bones. They communicate both with 
the lateral and the cavernous sinuses, and receive some small 
veins from the adjacent parts. 

There are also several small sinuses near the great occipital 
foramen, which communicate with the lateral sinuses, and also 
with the vertebral veins. They are called occipital sinuses. 

The brain or the whole of the soft substance contained within 
these membranes, is composed of four portions, viz. cerebrum, 
cerebellum, tuber annulare or pons Varolii, and medulla oblongata. 

Of the Cerebrum. 

The cerebrum completely fills the upper part of the cavity of 
the cranium. It has some resemblance to the half of an egg, 
which has been divided horizontally ; and is composed of two 
equal parts, which are separated vertically from each other by 
the falx. This vertical separation does not extend through the 
centre of the cerebrum, although it divides it completely before 

* An English anatomist, who flourished near the end of the 17th century. 



346 CEREBRUM. 

and behind. A portion of the central part of the cerebrum, 
which is situated deeper than the under edge of the falx, is not 
divided. 

The upper surface of the two hemispheres is convex. The 
under surface is rather irregular ; it is divided in each hemi- 
sphere into three lobes: the anterior, the middle, and the 'posterior. 

The anterior lobes of the brain are situated on the front part 
of the base of the cranium, principally on the orbitar processes 
of the os frontis. 

The middle lobes are lodged in the fossae formed by the tem- 
poral and sphenoid bones. 

The posterior lobes rest chiefly upon the tentorium, over the 
cerebellum. 

Between the anterior and middle lobes is a deep furrow, cor- 
responding to the base of the cranium on which they rest, which 
is called the fossa Sylvii. 

Thj surface of the brain resembles that of a mass of small 
intestines, or of a convoluted cylindrical tube : it is, therefore, 
said to be convoluted. The fissures between these convolutions 
do not extend very deep into the substance of the brain. 

The whole surface of the brain, thus convoluted, is covered 
by pia mater ; which is connected to every part of the surface 
by an infinite number of small vessels and processes, that appear 
when this membrane is peeled off from the surface of the brain. 

The mass of the brain consists of two substances of different 
colours ; one of which is, for the most part, exterior to the other. 
The exterior substance is of a light brown colour, and is there- 
fore called cineritious, or cortical, from its situation. 

The internal substance is white, and is denominated the medul- 
lary. 

The proportion of this medullary part is much greater than 
that of the cortical. The cortical, however, surrounds it, so as 
to form the whole of the surface of the cerebrum, that can be 
strictly said to be exterior. 

The colour of the cortical part appears to be derived from the 
blood ; as its intensity seems regularly proportioned to the quan- 
tity of blood in the head. In subjects who have been plethoric, 



CORPUS CALLOSUM. 347 

or have had a determination of blood to the head, it is uniformly- 
high-coloured ; in pallid and exhausted subjects it is of a brighter 
colour. 

The medullary matter is uniformly white; but small red 
points appear upon its surface, when cut, which are the sections 
of vessels which carry red blood : and these points are larger 
and more numerous in plethoric, than in exhausted subjects. It 
is rather firmer than the cortical substance. 

These two substances are most intimately connected in the 
cerebrum, and indeed seem to be a continuation of each other. 
In some parts they are blended together ; and in other places, 
there are portions of cortical matter within the medullary. 

The division of the cerebrum into two hemispheres extends to 
a considerable depth from above, and also to a considerable dis- 
tance internally, from its anterior and posterior extremities; of 
course, the part which is undivided is in the centre. 

The cortical part covers also the surfaces, which are in the 
great fissure that forms the two hemispheres, and is occupied, in 
a great degree, by the falciform process of the dura mater. To- 
wards the bottom of this fissure, and below the falx, these sur- 
faces being opposed to each other, and in contact, are slightly 
united by adhesion of the membranes that cover them. 

The central part, which is not divided, and which must ap- 
pear at the bottom of the fissure, when the two hemispheres are 
separated from each other, is medullary ; being evidently a union 
of the medullary matter of each hemisphere. This undivided 
medullary part is equal to about one half of the length of the 
hemispheres; the fissures at each extremity extending inwards, 
about one-fourth of their length. On each side of it, a fissure, 
equal to it in length, extends horizontally into the medullary mat- 
ter in each hemisphere, about half an inch; the whole of this 
unconnected surface, the middle of which is directly at the bot- 
tom of the great fissure, is termed corpus callosum. 

When the hemispheres are cut away to the level of this sur- 
face, and the corpus callosum is examined, two raised lines ap- 
pear in the middle, which extend from one end of it to the other; 
and between them is a small groove of the same length. This 



348 LATERAL VENTRICLES. 

groove is called the raphe, or suture of the corpus callosum. 
From the raised lines or bands on each side of the raphe, small 
lines less elevated pass across the corpus callosum, and are lost 
in the medullary matter. The hemispheres being thus cut off at 
the level of the corpus callosum, on the cut surface is to be seen 
the interior mass of medullary matter, with the cortical part ex- 
terior, its edge exhibiting the convoluted surface of the brain, 
and the pia mater, following the convolutions. 

The medullary surface, thus exhibited, with the corpus cal- 
losum in the centre, is denominated the centrum ovale. 

In the brain there are four cavities called ventricles : three of 
these are formed in the substance of the cerebrum : the fourth is 
situated between the cerebellum, the pons Varolii, and medulla 
oblongata. The two largest are called the lateral ventricles, from 
their situations ; the others are named, from the order in which 
they occur, the third and the fourth ventricle. 

The lateral ventricles are cavities of an extremely irregular 
figure : they are situated in each hemisphere a little below the 
level of the corpus callosum : and, with the exception of the 
partition which separates them, are directly 'under it. They 
commence anteriorly, nearly on a line with the termination of 
the fissure that separates the two hemispheres anteriorly; and 
continue backwards almost as far as the commencement of the 
fissure that separates them posteriorly : when they have attained 
this length posteriorly, they form a considerable curve, first out- 
wards, then downwards, and afterwards forwards, so that they 
terminate almost as far forwards as they commenced ; but much 
deeper. 

At the posterior part of their curve, when they incline out- 
wards, previous to their turn downwards, a process or continua- 
tion of the cavity extends backwards, almost as far as the cere- 
brum does itself. These elongations are called the posterior 
cornua or sinuses, or the digital cavities. 

Each ventricle may, therefore, be divided into three parts, 
viz. The portion under the corpus callosum ; the portion which 
continues outwards and downwards, and terminates below it : 
and the posterior portion. 



CORPUS STRIATUM—THALAMUS NERVI OPTICI.-FORNIX. 349 

It has been compared to a ram's horn, by some who have 
contemplated particularly the upper and lower portions of the 
cavity ; and by others who have had the whole extent in view, 
it has been called tricornis. 

The bottom, or lower surface of these cavities, is varied in 
almost every part of its extent. The front part of the bottom of 
each ventricle is a broad and convex eminence, which becomes 
narrower as it proceeds backwards ; so that it resembles a por- 
tion of a pear. It inclines outwards as well as backwards, so 
that the narrow posterior extremities of the two bodies are far- 
ther from each other than the anterior broad extremities. 

The colour of these bodies is cineritious externally; but they 
are striated with medullary matter within, and therefore are 
called corpora striata. 

Between their posterior extremities are two other eminences, 
which incline to the oval form, and have a white or medullary 
colour; although their substance, when cut into, is slightly stri- 
ated : they are called the thalami nervorum opticorum. These 
bodies are very near each other: and, being convex in form, are 
in contact at the centre : they adhere slightly to each other ; and 
this adhesion is called the soft com?nissure, (commissura mollis.) 

The corpora striata, and the thalami nervorum opticorum, join 
each other at the exterior sides of the thalami: where they are 
in contact, there is the appearance of a narrow medullary band, 
which continues during the whole extent of their connexion: it 
has been called, by some, tenia semicircularis, from its form ; 
by others, centrum geminum semicirculare. 

These surfaces constitute the bottom or floor of the first por- 
tion of the ventricles, which is under the corpus callosum : upon 
this floor is laid a thin lamina of the medullary matter, of a tri- 
angular form, called the Fornix, which covers the thalami nervo- 
rum opticorum, and is attached to them by a membrane; so that 
when the ventricles are opened, the bottom appears to consist of 
the corpora striata, and the fornix. 

The upper surface or roof of the ventricles is concave ; from 
the middle of it, immediately under the raphe of the corpus cal- 
losum, there proceeds downwards a partition of medullary matter, 

vol. 11. 30 



350 SEPTUM LUCIDUM— PLEXUS CHOROIDES. 

which separates the two ventricles from each other. This is 
called septum lucidum, from its being nearly transparent : below, 
it adheres to the fornix, and anteriorly, it is continued into the 
medullary matter, between the corpora striata. This septum 
lucidum is formed of two lamina or plates, which are separated 
from each other in the anterior portion of the septum, and thus 
form a small cavity, which has no communication with the other 
cavities of the brain. 

The fornix is not perfectly flat, but accommodated to the sur- 
face of the thalami nervorum opticorum ; its under surface is 
rather concave, and its upper surface convex. The anterior 
angle passes down between the most anterior parts of the thalami 
nervorum opticorum, and is divided into two small portions called 
its crura, which can be traced some distance in that part of the 
brain. 

The body of the fornix is attached to the surfaces of the tha- 
lami nervorum opticorum, on which it rests by a very vascular 
membrane, which is spread over the thalami, and called tela 
choroidea and velum interpositum. At the edges of the fornix, 
there are manv blood-vessels in the membrane, arranged close 
to each other, which are called the plexus choroides. 

The posterior side or edge of the triangular fornix terminates 
in the corpus callosum, or the medullary matter which is above 
it at that place ; but the under surface is attached throughout to 
the parts on which it lies, by the aforesaid membrane. 

The two posterior angles of the fornix form what are called 
the crura, and they terminate in the following way. 

The surfaces of the inferior portions of the lateral ventricles 
are not uniformly concave ; but at the bottom of each there is 
a prominent body, which begins where this portion of the cavity 
winds outwards and forward, and continues its whole extent. 
This prominence has a curved form, and is marked by trans- 
verse indentations towards its extremity ; hence it has been 
termed the hippocampus, or cornu ammonis. 

A similar prominence, but smaller, and without the transverse 
indentations, is to be found in the posterior portion of the ven- 
tricle : this has, also, been called hippocampus ; but the terms 
minor and major are applied to distinguish them. 



COMMISSURES OF THE BRAIN. 35 J 

The posterior angles of the fornix terminate in the large hip- 
pocami; and the margin or thin edge of the two anterior sides 
of the fornix, is continued to form an edge to the hippocampus ; 
and is called the tcenia hippocampi, or corpus jimbriatum. 

The word fornix was the ancient name of a vault, or arch ; 
and, from its supposed resemblance to an arch, this part has been 
called by that name. 

When the fornix is raised up, which must be done by dividing 
it at the anterior angle, and detaching it from the thalami ner- 
vorum opticorum, by dissecting the velum interpositum, the tha- 
lami are brought fairly into view, and appear like oval bodies 
placed parallel to each other. They adhere slightly at their upper 
surfaces, and, when separated, a fissure appears between them, 
which is the third ventricle. At the upper and front part of this 
third ventricle, near its commencement, before the anterior crura 
of the fornix, and very near them, is a white chord, like a nerve, 
which passes across the ventricle, and can be traced to some 
distance on each side of the medullary matter of the brain. 

This chord is called the anterior commissure of the brain. The 
thalami nervorum opticorum being of an oval form, and touch- 
ing each other in the middle, there must be a vacuity between 
them at their extremities. This vacuity is behind the anterior 
crura of the fornix, and has been called Vulva, Iter ad Infundi- 
bulum, and Iter ad Tertium Venlriculum. 

It leads, of course, into the third ventricle ; but a passage con- 
tinues from it downwards and rather forwards, to the infundibu- 
lum ; which is a process somewhat resembling a funnel that is 
composed principally of cineritious substance, and passes from 
the lower and front part of the third ventricle, towards the sella 
turcica ; in which is situated the small body called the Pituitary 
Gland. 

The infundibulum is hollow at its commencement, and solid at 
its extremity near the gland. 

The adhesion of the thalami nerv. optic, to each other, at the 
upper part of the third ventricle, has been denominated the Com- 
ynissura Mollis. The recession from each other at their posterior 
extremities, in consequence of their oval figure, forms another 



352 COMiMUNICATION OF THE VENTRICLES. 

opening into the third ventricle, when the fornix and tela cho- 
roidea is raised, which is closed when they are in their natural 
situations upon it. 

In the back part of the third ventricle is another medullary 
chord, called the Posterior Commissure, which appears much like 
the anterior commissure; but does not extend into the substance 
of the brain in the same way. Under this chord, or posterior 
commissure, is a passage which leads to the fourth ventricle, 
called Iter ad Quartum Ventriculum, or Aqueduct of Sylvius. 

Behind the third ventricle, and terminating it posteriorly, are 
four convex bodies, called Tubercula Quadrigemina, or Nates 
and Testes : the nates are uppermost and most convex ; the testes 
are immediately below, and somewhat oval transversely. 

The nates and testes are situated so far backwards that they 
are near the anterior part of the upper surface of the cerebellum, 
and the anterior edge of the middle of the tentorium. The pos- 
terior part of the fornix is directly over them, but it unites with 
the medullary matter of the cerebrum above it ; there would, 
therefore, be a passage into the lateral ventricles from behind, 
between the back of the fornix which is above, and the nates 
and testes which are below; but the velum interpositum passes 
in from behind, and attaches the lower surface of the fornix 
to all the parts on which it lies ; and thus closes the ventricles at 
this place. In this membrane, immediately over the posterior end 
of the fissure called the third Ventricle, and in contact with the 
nates, is the Pineal Gland. This body is not so large as a pea, 
and is formed like a pine-apple, or the cone of a pine tree. 

When the fornix is raised, by dissecting the membrane, it may 
be elevated with the membrane and fornix. 

The nature of this body is not understood : it resembles a 
small gland in its appearance, but it is very soft; and particles 
of sand-like matter are often found in it. 

There is a small chord on each edge of the third ventricle, 
which appears to proceed from the pineal gland, and continues 
on the edge of the ventricle to the anterior crura of the fornix, 
to which it unites. These chords join each other under the 
pineal gland: they are called the pedunculi, or footstalks of the 
pineal gland. 



OF THE CEREBELLUM. 353 

The mrmbrane connected with the pineal gland, it has been 
said, is the tela choroidea, or velum inter -positum, in which the 
plexus choroides is placed, at the edges of the fornix. This 
membrane is extended, somewhat thinner and less vascular, so 
as to line the surface of the ventricles. The plexus choroides 
appears to begin at the end of each of the inferior portions of 
the ventricles, where the pia mater penetrates from the basis of 
the brain: it proceeds into the upper portions of the ventricles, 
and continuing along the edge of the fornix, passes under that 
body at its inferior angle, and meets the plexus of the opposite 
side. Between this meeting of the plexus, and the crura of the 
fornix, is a vacuity of an oval figure, which forms a communi- 
cation between the ventricles of the brain. Under this vacuity 
or foramen, the thalanii ncrv. optic, recede from each other, 
and from the anterior passage into the third ventricle, described 
at page 351, so that at this place the three ventricles communi- 
cate with each other. 

From the plexus choroides of each side, where it has 
passed under the fornix at the anterior angle, a large vein is 
turned backwards, so as to run nearly over the fissure of the 
third ventricle towards the pineal gland. Several veins from the 
surface of the ventricle join this vein near its commencement; 
thus formed, it passes along with the corresponding vein from 
the opposite side, sometimes in contact and sometimes separated 
to a small distance; near the pineal gland, these veins unite into 
one trunk, the great internal vein of the brain, called the Vena 
Galeni: which terminates soon after in the torcular Herophili. 

Of the Cerebellum, 

The cerebellum is situated in the lower and posterior part of 
the cavity of the cranium, in contact with that portion of the os 
occipitis which is below the groove for the lateral sinuses. It is, 
of course, much less than the brain. 

It is covered above by the tentorium, and is divided below into 
two lobes, by the falx minor. 

The surface of the cerebellum differs in some respects from 
that of the cerebrum. Instead of the convolutions, there are 

30* 



354 pons VAROLII. 

small superficial depressions, which are nearly horizontal, tending 
to divide the cerebellum into strata. The pia mater extends into 
these depressions ; and the tunica arachnoidea passes over them, 
as in the cerebrum. 

The exterior part of the cerebellum is composed of cineritious 
or cortical, and the internal or medullary matter, as is the case 
with the cerebrum : but the proportions of these substances in 
the cerebellum, are the reverse of what they are in the cerebrum. 

If sections be made in the cerebellum, the medullary matter 
is so arranged that it appears like the stem or trunk of a plant, 
with ramifications extending from it. This appearance has been 
called the Arbor vitce. 

On the basis of the brain is a part called Tuber Annulare, or 
Pons Varolii, which is formed by processes from the cerebrum, 
and cerebellum ; and is in contact with the anterior and inferior 
portion of the cerebellum in the middle. From this part the 
medulla oblongata proceeds downwards and backwards, under 
the cerebellum : and between the cerebellum, the medulla oblon- 
gata, and the pons Varolii, is the vacuity, called the fourth ven- 
tricle of the brain. 

When the brain is in its natural situation, this cavity is below 
and behind the nates and testes ; and from the cerebellum there 
passes up to the testes, a lamen of medullary matter, which 
closes it above. This lamen is called the Valve of Vieussens, or 
the Valve of the Brain. Below, the ventricle is closed by a 
membrane, which connects the medulla oblongata to the cere- 
bellum. 

There is a passage into this cavity from the third ventricle, 
which passes under the posterior commissure, and the nates and 
testes, and enters it below the testes. 

Of the Basis of the Brain, and the JVerves which proceed from it. 

When the brain is detached from the basis of the cranium, 
and inverted, (which can be readily done, if the nerves that 
proceed from it are divided, as it is inverted,) the tunica arach- 
noidea appears more conspicuous on the basis than it is on the 
upper part ; and the pia mater is disposed round the convolutions 
in the same manner that it is above; but the nerves and vessels 



BASIS OF THE BRAIN, AND NERVES PROCEEDING FROM IT. 355 

connected with the surface of the brain are so much involved 
with these membranes, that considerable dissection is required 
to expose them properly. 

The anterior and middle lobes of the brain are very con- 
spicuous on the inverted surface. The anterior lobes appear 
separated from each other by the extension of the great fissure 
which forms the two hemispheres. The middle lobes appear at 
some distance from each other in the centre ; and the cerebellum 
forms the posterior and most prominent part of the surface. 

When the brain has been carefully detached from the cranium, 
and the nerves adhering to it are preserved, the olfactory or first 
pair* of nerves, appear on the anterior lobes, running nearly 
parallel to each other at a small distance from the great fissure. 
They are flat, and thin, and soft, in their texture ; their breadth 
is rather more than one-sixth of an inch. They pass in three 
divisions from between the anterior and middle lobes of the 
cerebrum, which soon unite and run to the cribriform plate of 
the ethmoid, where they expand into soft bulbous lobes, from 
which proceed the fibres that perforate the cribriform plate, and 
are spread upon the Schneiderian membrane. 

Behind the olfactory nerves are the optic. Each of which 
come out between the anterior and middle lobes of the cere- 
brum ; and after bending so as to meet its fellow, turns off and 
passes through the optic foramen in the sphenoidal bone. These 
nerves can be traced in the brain to the thalami nerv. optic. 

In the angle formed by the optic nerves posteriorly, is a mass 
of softish cineritious matter (pons Torini) ; and also the infundi- 
bulum which passes to the sella turcica. 

In this soft cineritious matter are two round white bodies that 
resemble peas ; which are called the Corpora Albicantia of Willis, 
or the EminenticB Mammillares. Behind these bodies are two 
large medullary processes, called the Cru?'a Cerebri, which are 
best seen if some of the cortical part of the adjoining middle 
lobes is dissected away. They come from the medulla of the 
opposite sides of the brain, and gradually approach each other 
until they arrive at the tuber annulare, or pons Varolii. 

* The nerves are numbered from before. 



356 MEDULLA OBLONGATA. 

The Pons Varolii* is a mass of considerable size, which has a 
medullary appearance externally, but is striated within: it is 
formed by the union of the two above mentioned crura cerebri, 
and of two similar processes derived from the cerebellum, called 
also its Crura. It lies over a part of the body of the sphenoid 
bone, and of the cuneiform process of the occipital bone, and 
under a portion of the middle lobes of the cerebrum and of the 
cerebellum. There is a longitudinal depression on its surface, 
made by the basilar artery ; and there are also many transverse 
streaks on i f . 

The crura of the cerebellum, which runs into this substance, 
are evidently continued from the arbor vitee or medulla of the 
cerebellum. 

The anterior edge of the cerebellum, part of which is in con- 
tact with the pons Varolii, is remarkably prominent on each side 
of it. These prominences are called the Vermes of the cere- 
bellum. 

The medulla oblongata is continued backwards from the pos- 
terior side of the tuber; and somewhat resembles a truncated 
cone inverted. 

It lies on the cuneiform process of the occipital bone, and 
extends to the foramen magnum. It is indented lengthwise, both 
anteriorly and posteriorly, by fissures which are very evident : 
it is composed of medullary matter externally, and cineritious 
matter within. 

On each side of the anterior fissure, which is in view when 
the brain is inverted, are two oblong convex bodies: those which 
are next to the fissure are called the Corpora Pyramidalia, and 
are the longest ; the two exterior are called Corpora OHvaria, 
and are not so long. 

The third pair of nerves come from between the crura of the 
cerebrum, and pass forward, diverging from each other. They 
proceed by the cavernous sinus, and, after penetrating the dura 
mater, go out of the cranium at the foramen lacerum. 

The fourth pair, the smallest nerves of the brain, resemble 
sewing thread in their size and appearance. They come out 

* Named from Varolius, physician to Gregory VIII. in 1573. 



NERVES OF THE BRAIN. 357 

between the cerebellum and pons Varolii, but can be traced 
backwards as far as the testes. They proceed forwards by the 
sides of the pons Varolii, and after penetrating the dura mater 
near the posterior clinoid apophysis, pass through the foramen 
lacerum to the trochlearis muscles of the eye. 

The fifth pair, the largest of the brain, arise from the crura 
of the cerebellum, where they unite with the pons Varolii : they 
pass forwards and downwards, and penetrate the dura mater 
near the point of the petrous portion of the temporal bone. 

This nerve appears like a bundle of fibres ; and, under the 
dura mater, forms a plexus ; from which its three great branches 
proceed to their destination. 

The sixth pair arise from the medulla oblongata, where it 
joins the pons Varolii. It is often composed of two chords on 
each side, one of which is very small ; they pass under the pons 
Varolii, and through the cavernous sinus, with the carotid artery : 
after emerging from this sinus they proceed through the foramen 
lacerum to the abductor muscles of the eye. In this course a 
small twig passes from it, which accompanies the carotid ar- 
tery through the canal in the petrous portion of the temporal 
bone, and with a twig from the fifth pair, is the origin of the in- 
tercostal nerve. 

The seventh pair appear at the side of the medulla oblongata, 
near the pons Varolii. It is composed on each side of two chords, 
called Portio Dura and Portio Mollis, and of one or more small 
fibres between them, called Portio Media. The portio mollis can 
be traced to the fourth ventricle. The portio dura seems to arise 
from the place of union of the pons Varolii with the medulla 
oblongata and the crura cerebelli. The portio media appears to 
originate in the same neighbourhood, and may be considered as 
an appurtenance of the portio dura. They all proceed to the 
meatus auditorius internus, as it has been called, in the temporal 
bone. 

The eighth pair of nerves arise from the corpora olivaria on 
the side of the medulla oblongata. They are composed in each, 
of one chord called the Glosso-Pharyngeal, and of a considerable 
number of small filaments, which unite and form another chord 
called the Par Vagum. 



358 EIGHTH AND NINTH PAIR OF NERVES. 

With these nerves is associated a third chord, called the Spi- 
nal Accessory Nerve of Willis, which passes up the spinal cavity, 
being composed of twigs from the posterior and anterior portions 
of almost all the cervical nerves. 

The par vagum, with this nerve and the glossopharyngeal, 
proceeds from its origin to the foramen lacerum formed by the 
occipital and temporal bones ; where they all pass out of the 
cranium; separated from each other, and from the internal jugu- 
lar vein, by small processes of the dura mater. 

Their destination is extremely different. The glossopharyn- 
geal is spent upon the tongue and pharynx ; the par vagum upon 
the contents of the thorax and abdomen, &c, while the accessory 
branch, which seems to have no connexion with them, perforates 
the sterno-mastoid muscle, and is distributed among the muscles 
of the shoulder. 

The ninth pair arise from the corpora pyramidalia by many 
filaments, that are united on each side into three or four fasciculi, 
which perforate the dura mater separately, and then unite to pass 
out of the anterior condyloid foramen of the occipital bone : 
this pair is spent upon the muscles of the tongue. 

Within the last three or four years, there have been many allusions in the 
public papers, to the discoveries of Dr. Gall, formerly of Vienna, respecting 
the brain. For information concerning these discoveries, the reader is re- 
ferred to a very learned and judicious Memoir, presented to the class of 
Mathematical and Physical Sciences of the National Institute of France, by 
Messrs. Tenon, Portal, Sabatier, Pinel, and Cuvier. 

A translation of this report has been published in the fifth volume of the 
Edinburgh Medical and Surgical Journal for 1809. See, also, Lessons in 
Practical Anatomy by the present editor, part I. 

Galen taught that there were two motions in the brain, one caused by the 
pulsation of the arteries, the other by respiration, the air being admitted into 
the ventricles through the ethmoidal and sphenoidal cells. Vesalius and 
Fallopius refuted the latter opinion and exposed its error. In 1744, Mr. 
Scblichting, of Amsterdam, announced to the Royal Academy of Sciences 
of Paris, that the brain was elevated in expiration and depressed in inspira- 
tion. MM. Haller and Lamard repeated his experiments, and found that 
the motion of the brain depended on a reflux of blood through the internal 
jugulars, in cases of laborious respiration, besides the common motion from 
the pulsation of the arteries. — See Discours sur l'Anatomie par Lassus. — h. 



SPINAL MARROW. 



359 



CHAPTER XIII. 



OF THE SPINAL MARROW. 



The medulla oblongata is continued from the cavity of the 
cranium, through the great foramen of the occipital bone, into 
the great canal of the spine; when it takes the name of Medulla 
Spinalis, or Spinal Marrow. 

The dura mater passes with it through the great foramen, and 
encloses the whole of it. At the commencement of the spinal 
canal this membrane is attached to the surrounding bones; viz. to 
the margin of the great occipital foramen, and to the atlas ; but 
below this it is loosely connected by a membrane which sometimes 
appears to contain a little adeps. The tunica arachnoidea and 
the pia mater also invest the medulla spinalis. The arachnoidea 
appears unconnected with the dura mater; and it can easily be 
removed from the pia mater. The pia mater adheres rather 
firmly to the substance it encloses. 

The spinal marrow consists of medullary matter externally, 
and cineritious or cortical matter internally. 

The fissures which are observable, anteriorly, and posteriorly, 
in the medulla oblongata, are continued down the spinal marrow; 
dividing it partially into two lateral portions: these fissures pene- 
trate to a considerable depth. Each of the lateral portions is 
marked on its external surface, by a more superficial fissure, 
which partially divides it into an anterior and posterior part; so 
that a transverse section of the spine has a cruciform ap- 
pearance. 

The nerves go off in fasciculi from the anterior and posterior 
surfaces of each lateral portion of the spinal marrow; so that 
each nerve is formed of two fasciculi : one from before, and the 
other from behind. The fasciculi are of different sizes in different 
parts of the spine. The lowermost of the neck are large and 



360 MEDULLA SPINALIS.— LIGAMENTUM DENTICULATUM. 

broad ; those of the back are slender : and those of the loins, and 
upper part of the sacrum, are very large. 

The uppermost of the fasciculi of the spine proceed almost at 
right angles with the medulla spinalis, to the foramina through 
which they pass : those which are lower pass off in a direction 
obliquely downwards; and the lowermost are almost perpen- 
dicular. Between the anterior and posterior fasciculi, a fine liga- 
mentous chord passes, which is attached above to the dura mater 
as it passes through the foramen magnum, and continues to the 
os coccygis. It passes between the tunica arachnoidea and pia 
mater, attached to the pia mater by cellular membrane. It sends 
off a small process in a lateral direction, to be attached to the 
dura mater in the interstices between the places where the fasci- 
culi pass through the dura mater, and nearly in the middle be- 
tween the upper and lower fasciculi. 

The spinal marrow terminates in a point near the uppermost 
lumbar vertebra. The ligamenta denticulata of the opposite sides 
join each other at this point, and form a small chord, which, con- 
tinuing downwards, is inserted into the os coccygis. 

These ligaments may support, and keep fixed, the medulla and 
the nerves, as they originate from it. 

As the spinal marrow terminates at the upper lumbar vertebra 
the lumbar and sacral nerves go off above: they pass down like 
a bunch of straight twigs, and are called Cauda Equina, from a 
fancied resemblance to the tail of a horse. The sheath, formed 
by the dura mater for the spinal marrow, continues of its origi- 
nal size, and encloses them in one cavity. 

The posterior and anterior fasciculi pass out separately from 
the dura mater; after they are out, the posterior fasciculus forms 
a ganglion ; from which one nerve passes that joins the anterior 
fasciculus, and thus forms the spinal nerves. 

When the nerves go off, either from the spinal canal, or the 
cavity of the cranium, the external lamen of the dura mater 
where they pass out, attaches itself to the bone or the periosteum ; 
while an internal lamen, together with the pia mater, and, per- 
haps, the tunica arachnoidea, is continued with the nerve. 



VEINS OP THE SPINAL MARROW. 361 

This process from the dura mater becomes so much changed, 
that it has been considered as cellular membrane. 

The pia mater and tunica arachnoidea seem also to invest, not 
only the nerve in general, but the fibres of which it is composed. 
On this account, probably, the nerves are larger after passing 
through the dura mater, than they are when they leave the brain 
and spinal marrow. 

The arteries of the Spinal Marrow proceed from the head, and, 
with several additions, continue downwards to the lumbar ver- 
tebrae. 

There is, generally, one artery on the front surface of the 
medulla, which is formed by the union of two branches, that 
arise from the vertebral arteries within the cranium. This ar- 
tery proceeds downwards and communicates with those of the 
neck, and with the intercostal arteries, by the intervertebral for- 
amina, so that it preserves its size. 

It terminates with the spinal marrow ; and the cauda equina 
below it, is supplied by branches from the internal iliac, which 
enter through the foramina of the sacrum. 

There are, generally, two arteries on the posterior surface of 
the medulla spinalis, which also pass out from the cranium ; 
arising from the vertebral arteries or inferior arteries of the cer- 
ebellum; they have a serpentine arrangement, and communi- 
cate with each other, and with the ramifications of the anterior 
spinal artery. 

All of these arteries are dispersed upon the spinal marrow and 
its membrane, and the parts immediately contiguous. 

The veins correspond with the ramifications of the arteries; 
but they are collected into two larger branches called the Sinus 
Venosi; which are situated exterior to the dura mater, on the 
front and lateral sides of the spinal canal. They extend the 
whole length of the canal, and entering the great occipital fora- 
men, communicate with the lateral and occipital sinuses. 

VOL. II. 31 



362 THE EYE 



CHAPTER XIV. 



OF THE EYE. 



It will be very proper to read the description of the orbit of the eye at page 
106, volume 1st, as an introduction to the following description of the 
organ. 

In addition to that account of the bones, it is to be observed that processes 
of the dura mater pass through the foramina optica and lacera, which line 
the cavity of the orbit, and unite with the periosteum at the margin of it. 

The eye is an optical instrument of a spherical form, which 
lies in the orbit, in the bed of cellular membrane, more or less 
filled with adeps for the convenience of its motions. Connected 
with the ball of the eye, are several auxiliary parts which are 
calculated for its motion and protection, as well as accommoda- 
tion in other respects. 

Of the parts auxiliary to the Eye. 

Above the upper margin of the orbit, on the prominences of 
the os frontis, called superciliary ridges, the adipose membrane is 
commonly more full than it is in the other contiguous places ; and 
the skin which covers it is thereby rendered prominent. 

The supercilia or eyebrows grow out of this prominent skin. 
The hairs which compose them are placed obliquely, with their 
roots towards the nose. Their principal use seems to be to de- 
fend the eye from sweat, and other matters which roll down the 
forehead. They are moved by the corrugator muscle, and thus 
express certain passions ; and they are also moved by the occi- 
pito-frontalis and orbicularis palpebrarum. 

— The extent and degree of curvature of the eyebrows, differ 
much in different individuals. The hairs of which they are com- 
posed, are short, curved, highly elastic, and arranged in rows, 



THE EVELIDS. 363 

the middle of which are the longest. The internal extremities of 
the eyebrows, called the head, occasionally meet; but most usually, 
there is an interval between them called glabella, which presents 
the smoothness and polish of other parts of the forehead, and 
adds to the open and noble expression of the face. The outer 
extremity or tail is terminated by a thin series of hairs, (cauda 
supercilii) near the outer angle of the frontal bone. The colour 
corresponds generally with that of the hair. — 

The Eyelids or Palpebrce, 

Are formed by a slit or orifice in the skin (fissura palpebra- 
rum) ; immediately under the skin, surrounding this orifice, is a 
portion of the orbicularis muscle ; under this portion of the mus- 
cle, there is a plate of cartilage, and under the cartilage, a por- 
tion of tunica conjunctiva, or membrane that covers the front 
part of the ball of the eye and lines the eyelids. 

— The eyelids, may be considered two movable fleshy cur- 
tains, nicely adjusted to one another at their free edges, and to the 
anterior surface of the ball of the eye, which they exactly cover. 
— They are composed of the skin externally, which is so thin as 
to allow the light partially to pass through it, and which is fold- 
ed inwards at the free margin of the lids, so as to line their inner 
surface, where it takes the character of mucous membrane, 
(tunica conjunctiva) ; from the lids, it is reflected again over 
the anterior surface of the eyeball, so that the conjunctival 
linings of both eyelids form one continuous membrane. The 
lids are two in number, upper and lower, palpebra superioris, 
palpebra inferioris. They are divided unequally by the trans- 
verse fissures ; so that the upper lid is considerably the larger. 
Was it not for this, as the motions of the lower lid are very 
limited, the eye would be only half uncovered, in what is called, 
opening the eye. 

— The fissure which separates the lids is not exactly transverse; 
it is slightly depressed externally. The reverse is said to be the 
case in regard to the Chinese, in whom the peculiar expression 
of the eye depends upon the depression of the internal angle 
below the level of the outer. 



364 THE EYELIDS. 

— The cellular tissue of the eyelids is very lax, but comprises 
none of the adipose. Hence the lids may suffer from cedema- 
tous or sanguineous effusions, but are never burthened with fat. 
The two lids unite at the extremities of the transverse fissure, 
and from two angles, or canthi, the internal of which is the 
largest, and is call the great canthus. This is owing to the in- 
sertion of the orbicularis at the internal canthus upon a round 
tendon, which does not exist at the outer. — 

The upper eyelids, therefore, are composed of the skin, of 
some fibres of the orbicularis muscle, of the tendon of the levator 
palbebrae superior muscle, of the cartilaginous plate, and of the 
tunica conjunctiva. The under eyelid is formed in the same way, 
with the exception of the cartilage, which, in it, is confined to 
the margin. There is besides no muscle or tendon in this lid 
analogous to the levator palpebral superioris. 

These cartilages form the margin of each eyelid, which is 
called Tarsus. The upper cartilage is broad in the middle, and 
narrow at each extremity, and accommodated to the form of 
the eyeball and eyelid. The under cartilage is a narrow flat rim, 
which does not extend far from the margin of the eyelid. A thin 
delicate membrane is extended from the upper and lower mar- 
gins of the orbit to these cartilages, and has been considered as 
forming ligaments for them. 

— These cartilages are closely connected together by some 
fibrous matter* at the external canthus, but terminate short of 
each other at the internal, by an attachment to the bifid extremity 
of the round tendon, in order to allow space for the lachrymal 
puncta and ducts. The superior tarsal cartilage, is much broadest 
in the middle, where it is about six lines wide. The inferior is 
about two lines in breadth, and is nearly of the same width in its 
whole extent. Their adhering borders, degenerate into cellular 
tissue, by which they are connected to the fibrous layer of the lids. 

* This fibrous matter, is part of a thin ligamentous expansion continuous with 
the periosteum of the socket, attached to the margin of the tarsal cartilages, and 
placed between the conjunctiva and orbicularis muscle. It is sometimes called 
ligamentum latum palpebrarum, — p. 



TARSAL CARTILAGES—TUNICA CONJUNCTIVA. 355 

They present on their inner surface a number of vertical grooves 
in which are lodged the glands of Meibomius. — 

Their edges are formed obliquely, and apply to each other in 
such way, that when the lids are closed a groove is formed be- 
tween them and the eye ; by which the tears are conveyed 
towards the nose. 

The use of these cartilages is to keep the eyelids properly ex- 
panded; and to form margins that apply accurately to each 
other. 

These cartilages are covered internally by the tunica conjunc- 
tiva. 

The levator palpebral muscle, which arises from the bottom of 
the orbit, at the upper part of the foramen opticum, and passes 
over the superior muscle of the eyeball, is inserted by a broad 
thin tendon or aponeurosis into the cartilage of the upper eyelid, 
and draws it upwards, within the upper margin of the orbit, 
when the eyelids are opened. 

The antagonist muscle to the levator or that which closes the 
lids, is the orbicularis palpebrarum. 

The tunica conjunctiva, that lines the eyelids, is continued 
from them, without any interruption of the surface, over the an- 
terior part of the ball of the eye ; in the same manner that the 
reflected membranes are continued from one surface to another. 

Although this membrane is a continuation of the skin, it is 
essentially different from its structure; being extremely thin, 
flexible, and sensible, and also transparent. It abounds with 
vessels, which do not carry red blood in their natural state, but 
receive it largely when they are inflamed or much relaxed. It 
adheres firmly to the cartilage at the edge of the eyelids; and 
becomes more loose in its adhesion to the lids, as it proceeds 
backwards. It is so reflected to the ball of the eye, that it 
covers and adheres to about one-third of it anteriorly. Where 
it first joins the eye, the adhesion is loose, but this adhesion be- 
comes firmer as it advances over the eye ; and it cannot be sepa- 
rated from the cornea without maceration, and a slight degree 
of putrefaction. The part immediately connected with the cor- 
nea is extremely thin and delicate. 

31* 



366 GLANDS OF MEIBOMIUS. 

This membrane closes the orbit of the eye, and completes the 
cavity which contains the muscles, lachrymal gland, &c, which 
are by this means precluded from contact with the external air. 

— The conjunctiva receives some very delicate nervous fibrils 
from the branches of the fifth pair, called the lachrymal and internal 
nasal. It contains, there is reason to believe, many mucous cryptae 
or follicles, but from their minuteness, it is difficult to detect 
them. Stachow, however, asserts that with the microscope he 
has seen them most distinctly, though in the palpebral conjunctiva 
only. According to this observer they are most numerous in the 
upper lid, and in the neighbourhood of the tarsal cartilages; 
especially at their extremities. 

— He found them in groups of 8, 12, or 15 together, and some- 
times 50 or 60. That portion of the ocular conjunctiva which 
covers the sclerotica is sometimes called the tunica adnata. — 

On the inside of each eyelid, apparently between the tunica 
conjunctiva and the cartilages, are a number of lines running 
inwards from the edge of the lid. These lines are of various 
lengths, from one-fourth to near half an inch ; the longest are in 
the middle of the upper lid. Some of them are straight; and 
others are serpentine: their colour is a yellowish white. There 
are generally more than thirty in the upper eyelid, and more than 
twenty in the lower. They are called the glands of Meibomius.* 
By pressure a sebaceous substance can be forced out of them, in 
the form of fine threads, from orifices on the edges of the eyelids. 
They are follicles into which the sebaceous substance is secreted. 
This substance appears to have a twofold effect: it prevents the 
tears from running over the eyelid, as any other unctuous matter 
would do, and it prevents the eyelids from adhering to each other, 
in consequence of their contact during sleep. 

— The orifices of these glands, are very minute, but will admit 
of the introduction of fine bristles. They are disposed in one or 
two ranges, immediately behind the eyelashes, and presenting 

* Charles Etienne demonstrated the little sebaceous glands of the eyelids, and 
Casserius caused them to be drawn and engraved a long time before Henry Meibo- 
mius. The latter gave his name to them by a letter printed in Helmstadt in 1666, 
in which they were accurately described. Sec Lassus. — h. 



EYELASHES—LACHRYMAL GLAND. 



367 

toward the eyeball. These orifices lead into the little lines or 
ducts, which Meibomius described as glands. But the gland of 
Meibomius is now known to be a compound follicle, or rather a 
series of minute glands ranged parallel with each other upon the 
sides of the duct into which they open ; some of which communi- 
cate together by lateral openings. The oily matter which they 
deposit on the edges of the lids, serves, in the ordinary state of 
the eye, to confine the tears, as water is known not to pass so 
readily over a vessel, the margin of which is greased. — 

The eyelashes or cilia are placed near the outer edge of the 
lower part of the cartilnges of each eyelid. They are always 
more or less curved, and their convexities are opposed to each 
other. By this arrangement the eye is defended from small 
external objects, and from light to a certain degree, without 
closing the lid completely. 

— The cilia consists of three or four ranges of hairs irregu- 
larly placed, the middle of which are longest, and which gives to 
the brush of hairs, a pencillous arrangement. They are strongest 
and most numerous in the upper lid. Their bulbs or follicles are 
placed between the skin and tarsal cartilages;* and of course 
are not met with in the internal canthus. The lashes, or cilia 
are covered by an oily fluid, secreted by a number of little retic- 
ular follicles, common to the roots of all hairs. This secre- 
tion tends to keep the hairs separate, and prevents that aggluti- 
nation that would otherwise take place, from the drying of the 
lachrymal fluid, mixed as it is with the Meibomian secretion. — 

It is necessary, for the perfection of the eye, that the whole 
surface covered by the tunica conjunctiva, viz. the anterior part 
of the eyeball and the internal surfaces of the eyelids, should be 
kept perfectly flexible and moist; for this purpose the lachrymal 
fluid is constantly secreted, in varying quantities, by the lachry- 
mal gland, formerly called Glandula Innominala.f 

* The tarsal cartilages thus intervene between the bulbs of the cilia and the Mei- 
bomian glands. And upon this is founded Berlinghieri's operation for the cure of 
Trichiasis, by the extirpation of the bulbs of the glands — p. 

t The necessity of this gland, exists only in land and amphibious animals, in which 
the eye is exposed to the evaporating effects of the air. In fishes, &c, it is not met 
with. The eyes in them being moistened by the fluid in which they live. — p. 



ogQ LACHRYMAL GLAND. 

This body is situated in a depression, in the upper surface of 
the orbit, near its external margin : it is exterior to, and above, 
the tunica conjunctiva. It is of an irregular oblong form, and 
rather flat; but it has some thickness. The under surface is 
lobulated, and forms two principal lobes. 

From the anterior edge of the gland the excretory ducts, to 
the number of six or seven, pass off. They terminate at a short 
distance from the gland, near the upper end of the cartilage, and 
near the external angle of the eye. They do not communicate 
with each other. 

Those ducts are so small, they are often not to be seen by the 
naked eye; but there is sometimes a chain of smaller glands, 
which lie between the gland and the eyelid, nearly in the di- 
rection of the ducts. 

— The lachrymal gland, is about the size of a bitter almond, 
and consists in a great number of little fleshy granules of a 
reddish white colour, in which, the extreme branches of the ar- 
teries terminate, and from which, minute excretory ducts are 
believed to originate. The granules are separated from each 
other by processes of cellular tissue, which are sent in by the 
general cellular envelope of the gland, and by nerves and blood- 
vessels. The excretory ducts originating from these glandular 
grains, form by inosculation the six or seven ducts above men- 
tioned, which open through the conjunctiva. The orifices in the 
conjunctiva, are readily seen in the eye of bullocks, but in the 
human eye, cannot well be discovered, without some artificial 
preparation. 

— After immersing the human eye, for some time in water co- 
loured with indigo, ink, or blood, the orifices become visible, and 
the ducts may be filled with mercury up to the gland. The ducts 
are three or four lines in length. — 

The fluid secreted by this gland, (viz. the tears,) is transparent, 
but is always salt to the taste. When evaporated, by exposure 
to the air, some cubic crystals, and a small quantity of mucilagi- 
nous matter remain. Chemistry has ascertained that these 
crystals contain muriate of soda, and soda uncombined, and that 
phosphate of lime and phosphate of soda may be obtained by 



PUNCTA LACHRYMALIA. ggg 

burning inspissated tears ; but the whole of the saline matter 
does not amount to one-hundreth part of the tears in which they 
are dissolved. The tears, therefore, consist of these salts, and of 
mucus, dissolved in a large proportion of water. 

The tears are carried from the eye by two small canals, which 
commence, one on each eyelid, at the internal extremities of the 
cartilages, opposite to each other.* 

The orifices of these canals, being in small cartilages, (but not 
in those called the tarsi,) are always open, and are called the 
Puncta Lachrymalia. 

Each of these canals runs, within the edge of each eyelid, 
from the place of its commencement to the lachrymal sac, which 
is a larger membranous canal situated in the depression formed 
by the anterior portion of the os unguis and the corresponding 
portion of the upper maxillary bone; and extending thence along 
the bony canal, which continues from this depression into the 
nose, and terminates under the inferior spongy bone near its 
anterior extremity. 

These canals are very small at their commencement at the 
puncta lachrymalia; but this small portion is very short; it forms 
an angle with the remainder of the canal, which is considerably 
larger.f 

The canals gradually approach each other as they proceed 
towards the lachrymal sac, into which they enter, in contact 
with each other, but by distinct orifices. 

— The orifices in the puncta are sufficiently large to admit 
readily a small bristle or probe. The ducts which lead from 
the puncta to the lachrymal sac, (see Fig. 1, Plate xiii,) are 
called canalicula lachrymalia. They are not straight; they 
commence by ascending perpendicularly in the upper, and by 
descending in the lower lid, for a line and a half; they are then 
turned at a right angle upon themselves, and pursue a course 
nearly horizontal to the lachrymal sac. Where the ducts turn 

* The little hollow at the internal canthus, in front of the caruncle, and where 
the tears collect before entering the puncta, is called the lacus lachrymalis. — p. 

t These canals were known to Galen, and were particularly described by Fa- 
lopius in 1584. — h. 



370 LACHRYMAL SAC AND DUCT. 

to form the angle, a sensible dilatation takes place, in which are 
found one or two minute mucous cryptas,* which sometimes 
embarrass the surgeon in operating through the ducts, the end 
of the probe or tube becoming entangled in the lower folds. — 

About one-fourth part of the lachrymal sac is situated above 
the junction of the two eyelids, or the tendon of the orbicularis 
muscle ; and the remainder below. After it descends below the 
orbit of the eye, it contracts and takes the name of the Lachrymal 
Duct 

— The lachrymal sac is ovoidal in its form, and closed at top; 
it rises about two lines above the round tendon of the orbicularis 
muscle, which is immediately in front of it, and feels like a grain 
of rice. Its diameter is about equal to that of a common goose- 
quill. Anteriorly it is covered by the integuments, the tendon 
above alluded to, and the orbicularis muscle. Externally it is 
bounded by the caruncle, and conjunctiva. — 

The sac and duct have some resemblance to the Schneiderian 
membrane in structure ; and are defended with a similar mucus. 
The membrane of which they are composed, adheres to the pe- 
riosteum of the bony canal. 

— Their walls are composed of two membranes, a mucous 
and fibrous ; or rather of a mucous facing on a fibrous basis. 
The mucous membrane, is internal, contains a number of follicles, 
which secrete a lubrifying mucus, as in the urethra, and as in 
the latter organ are apt, when inflamed, to produce strictures or 
obstructions in the passage, and thus become one of the causes of 
fistula lachrymalis. 

— The length of the nasal duct is from four to six lines; about 
equal to that of the sac. The direction of the duct in its bony 
canal, is downwards, backwards, and slightly inwards. At its 
termination in the inferior meatus of the nose, (about seven lines 
from the root of the nasal process of the upper maxillary 
bone,) the mucous lining membrane is thrown into a sort of 
valvular fold, which sometimes obstructs the introduction of a 
probe into it, from the nostril. The swelling of this valve, in 

* Dalrymple, Anat, of Human Eye, p. 277. Lond. 1834. — p. 



CARIJNCULA LACHRYMALIS. 



371 



corysa, measles, &c, is said to be one of the causes of the ac- 
companying epiphora. — 

The tears appear to enter the puncta lachrymalia upon the 
principle of capillary attraction ; and to be propelled forwards 
by the motion of the eyelids and the pressure of the orbicularis 
muscle. 

Between the puncta lachrymalia and the termination of the 
eyelids, at their junction with each other, is a small angular 
space, which is occupied by a body called the Caruncula Lackry- 
malis; which is of a reddish colour, with a few small hairs 
growing out of it: it is supposed to be glandular, and to secrete 
a sebaceous substance. It has an effect in directing the tears to 
the puncta lachrymalia. 

— The caruncula lachrymalis, consists of a collection of small 
mucous glands, seven in number — substitutes for the Meibomian 
glands which are deficient in the internal canthus. Six of these 
glands are placed upon a common level, and the seventh is 
seated upon the top of the rest near their centre, making the 
caruncle conoidal in shape, and about the size of a grain of wheat. 
— The conjunctiva is spread over them, and is pierced by a 
number of small apertures, which are the orifices of the excretory 
tubes of these glands. Each duct is garnished with a small hair 
planted close to its orifice. — 

Between the caruncula lachrymalis and the cornea, the tunica 
conjunctiva, in many persons, forms a plait or fold, which is very 
obvious when the eye is directed inwards ; this has some analogy 
with the membrana nictitans, or third eyelid of certain animals, 
and has been called the Vol vul a Semilunaris; its principal use 
appears to be, to give increased facility of motion to the globe in 
an outward direction, from the looseness of its connexions 
between the lids and the ball. 

The muscles of the eye, described at page 276, &c, are to be 
ranked among the auxiliary appurtenances of that organ. 

[At the internal corner of the eyelids is a small muscle which 
I had occasion to observe for the first time in the winter of 
1821-2. It has, I believe, escaped the notice of other anato- 
mists till the present time. This muscle is about three lines broad 



372 TENSOR TARS[. 

and six lines long, and arises from the posterior flat surface of 
the os unguis near its junction with the os ethmoides, and passes 
forwards and outwards, lying on the posterior face of the lachry- 
mal ducts. As it approaches the junction of the lids, it splits into 
two parts, nearly equal, each of which is appropriated to a duct, 
and inserted along its course almost to the punctum lachrymale. 

To get a distinct view of it, the eyelids must be separated from 
the eye and turned over the nose, leaving the tendinous attach- 
ment of the orbicularis and ciliaris muscles. The semilunar 
valve is brought into sight by this process, which must be dis- 
sected away, and also the fat and cellular membrane beneath it. 
The muscle is now seen, and by passing bristles through the 
lachrymal ducts its connexion with them is rendered evident, at 
the same time that we get a good idea of its size, origin and 
insertion. 

While making this inspection, by turning the muscle a little 
aside, we shall be convinced of another fact of some importance* 
and which is equally neglected by most anatomists. It is, that 
behind the tendon of the orbicularis muscle a ligamentous matter 
passes from the corners of the eyelids to the flat part of the os 
unguis, which ligament would keep the corner of the eyelids from 
being deformed, notwithstanding the tendon of the orbicularis be 
cut through in the treatment of fistula lachrymalis. The lachry- 
mal ducts are included in this ligament, and pass through it into 
the sac instead of going along the edges of the eyelids, as is 
commonly asserted. 

This muscle appears to be intended to keep the puncta in con- 
tact with the ball of the eye. Dr. Physick has suggested, that it 
will also keep the edges of the eyelids applied to the eyeball in 
cases of extreme emaciation where the eye is much sunk. 
While investigating this subject, my attention was called by Dr. 
Harlan to a motion prevailing in the puncta lachrymalia, with 
which I was before unacquainted. The puncta project them- 
selves and retract much after the manner of an earth worm, and 
it is probable that the latter motion may be produced in some 
measure bv this muscle. 



OF THE BALL OF THE EYE. 373 

In consideration of some of the functions of this muscle, I have 
ventured to propose that it be called Tensor Tarsi.']* 

The tendons of the four recti muscles, being spread upon the 
anterior part of the ball of the eye, constitute a partial covering, 
which has been called Tunica AlbugineaA This tendinous ex- 
pansion does not extend to the edge of the cornea, but stops short 
of it by several lines.J 

Of the Ball of the Eye. 

The spherical figure of the eyeball depends upon a strong and 
firm external coat called the Sclerotica; which has an aperture 
in its anterior part, filled up with a transparent substance, deno- 
minated Cornea, that closes it perfectly. 

— The antero-posterior diameter of the globe of the eye, is 
greater than the transverse. The former is about ten or twelve 
lines, the latter about one line less. This difference is owing 
to the projection of the cornea, it being a section of a lesser 
sphere. A Transverse vertical section of the globe, taken 
at any part, will represent a perfect circle. In short-sighted 
persons, the antero-posterior diameter of the eye is greater 
still, relatively to the transverse. A similar difference exists be- 
tween the eyes of young and old persons, and which accounts in 
part for the change which time effects in the power of vision. 
The axis of the globe of the eye does not correspond with the 
axis of the orbit ; but is exactly parallel with that of the ball of 
the opposite side, except in cases of obliquity or squinting. The 
optic nerves running out in the direction of the axis of the orbits, 
must therefore reach the balls of the eyes, on the inner side of 
their axis. 

— The sclerotic coat forms about five-sixths of the globe of the 
eye. The cornea the remaining sixth. — 

* For a more full account of this muscle, see Horner's Anatomy. 

t This is no longer considered as a proper membrane ; it is inseparably connected 
with and forms a part of the sclerotic coat. The partial expansion of these tendons 
seen through the conjunctiva, gives a brilliant glistening appearance to the eye, 
from which is derived the common term,M>/it*e of the eye ; sometimes it is spoken 
of as the Adnata. — p. 

I By line, is meant one-twelfth of an inch. 

vol. 11. 32 



374 



BALL OP THE EYE. 



The sclerotica is lined by a thin and delicate membrane, the 
Choroides, which is in close contact with it, but does not extend 
over the whole internal surface of the eye, and is deficient in the 
whole of the part occupied by the cornea. 

On the internal surface of the choroides is spread the pulpy 
expansion of the optic nerve, called the Retina; the natural con- 
sistence of which is not much more firm than mucus. 

Within these coats is a ca- 
vity that corresponds with the J^g- 74*. 
figure of the sclerotica and 
cornea, but is divided by an 
incomplete membranous par- 
tition that separates the ante- 
rior part of it, which is cover- 
ed by the cornea, from the 
remainder. This partition is 
called Ms; and it has a circu- 
lar vacuity in the centre, di- 
rectly opposite to the middle 
of the cornea, which is deno- 
minated the Pupil Rays of 
light, which penetrate the transparent cornea, pass through the 
pupil into the posterior part of the eye. 

The eye, thus formed, is filled with several transparent sub- 
stances, called Humours. The greatest part of the cavity, pos- 
terior to the iris, is occupied by the vitreous humour, which is 
thus denominated, from its apparent resemblance to melted glass. 
In front of the vitreous humour, and directly behind the pupil, 
is a small body, with double convex surfaces, called the Crystal- 
line Lens. 




* Fig. 74 is a magnified representation of a vertical section of the eyeball, show- 
ing the arrangement of the exterior tunics, a, Sclerotic coat, b, Cornea. e,e, Inner 
surface of the choroid coat, d, Ciliary ligament, and on its inner face, the ciliary 
body and processes. /, Lens, in front of which is the aqueous chamber, divided into 
two parts by the iris, which is seen stretched across it, with a semicircular hole in 
it, which is a section of the pupil. Fig. 79, exhibiting the retina and hyaloid 
tunics, to which the lens also is added, may be considered as removed from the 
interior of the choroid coat of this figure— p. 



TUMCA SCLEROTICA. 375 

In the space between the lens and cornea is a thin fluid, deno- 
minated, from its consistency, the Aqueous Humour. 

Several of the parts, above enumerated, have exquisite delicacy 
of structure, and require a very minute description. 

Of the Tunica Sclerotica. 

The Tunica Sclerotica, or external coat of the ball of the eye, 
derives its name from a Greek word, which signifies to make 
hard. It is composed of opaque white fibres, of great firmness, 
which form a membrane of very close texture, that supports the 
globular figure of the eye. It is thicker behind than it is before; 
but the expansion of the tendons of the recti muscles gives it a 
partial additional covering. — At its thickest part, just at the outer 
side of the optic nerve, the sclerotica, is a line and a half thick. 
Immediately behind the insertion of the recti muscles, about half 
a line. The latter is the weakest part of the parietes of the eye- 
ball, and a blow applied upon the cornea will cause a rupture at 
that part, rather than at any other. — 

It has been considered, by many anatomists, as continued into 
the cornea ; but it can be separated from it by putrefaction ; and 
it is essentially different from it in structure. 

The aperture in it, which is occupied by the cornea, is not per- 
fectly circular, but inclines somewhat to the oval form, the trans- 
verse diameter being rather longer than the vertical. 

Posteriorly, it is intimately connected with the optic nerve, 
which enters it, not directly at the extremity of the axis that 
passes through the centre of the cornea and pupil, but on the 
inside of this spot. 

The optic nerve has a firm coat (neurilema) which invests it 
rather loosely ; this coat seems to be continued into, or expanded 
upon the sclerotica. Within it, the delicate nerve diminishes 
considerably before it perforates the sclerotica, and appears to be 
composed of fibres. At the small place of its penetration, the scle- 
rotica is very thin ; and it seems that the nerve does not penetrate 
through one aperture, but these fibres pass separately through 
very small foramina, in this thin part. The foramina are neces- 
sarily very small, as the diameter of the whole perforated portion 



376 



CORNEA. 



in some eyes, does not exceed two lines, or one-sixth of an 
inch.* 

The sclerotica, in its natural state, has few, if any, vessels, that 
carry red blood. The great vascularity, which is so evident 
in ophthalmia, is in the tunica conjunctiva. 

— It is perforated posteriorly immediately around the optic 
nerve, with a great number of oblique foramina, through which 
the ciliary arteries and nerves enter. A little in front of these 
are seen other orifices, by which the veins emerge from the 
interior ; and near its junction with the cornea, a few are met 
with, which allow of the entry and exit of vessels, directly upon 
the iris. These latter vessels become very apparent in iritis, but 
present a hue less intensely bright, than those more superficial, 
which are involved in simple conjunctivitis. — 

The Cornea. 

The transparent membrane which fills up the vacuity in the 
anterior part of the sclerotica, is denominated Cornea, from its 
resemblance to horn.f It is said to be superior in strength to the 
sclerotica ; and it is also very firm. It is formed of lamina, that 

* We find one or two of these larger than the rest, for the transmission of the 
central artery and vein of the retina. The space occupied by these foramina, is 
called the lamina cribrosa, or sieve-like plate of the sclerotica. The optic nerve is 
made up of bundles of medullary filaments, each of which is enclosed in a minute 
envelope of cellular tissue, which is a process reflected inwards from the general 
neurilema of the nerve. By opening the eye, and removing all the coats but the 
sclerotic, and then squeezing slightly and pressing forward the nerve, in the direc- 
tion of the ball, the medullary matter will be seen to exude through the foramina 
of the cribriform plate. — p. 

t The neurilema of the optic nerve which is an emanation from the dura mater 
of the brain, is lost upon the sclerotic tunic. Hence, Galen, and many writers since 
him, even Zinn and Meckel, consider the sclerotic coat as derived from the dura 
mater. Many have also described the choroid as derived from the pia mater. It 
is better, however, to adopt the opinion of Albinus, Winslow, and others, that these 
coats are peculiar and expressly adapted to the eye, and that the sheath of the optic 
nerve, is continuous with the sclerotic without abruptness, by a sort of insensible 
change, always seen when one membrane terminates in another. This theory of 
formation, besides, is not borne out by comparative anatomy ; for in scaly fish, 
where the dura mater is membranous, the sclerotica, is corneous or bony. — p. 



CORNEA. 377 

are separable from each other, which are supposed to be con- 
nected by a very delicate cellular membrane. 

This cellular membrane appears sometimes to contain a fluid; 
for, if a section be made of the coats of the eye, and pressure be 
applied to the cornea, an exudation will be perceived, both upon 
its internal and external surfaces. 

— The cornea is composed of six or seven distinct lamella, 
laying over each other, like the leaves of a book, and which may 
readily be separated by maceration. The cellular tissue which 
connects them is so loose as to enable us to slide the layers 
slightly over one another between the thumb and finger. The 
cells of this tissue are filled with a fluid; hence it has been called 
by some writers, substantia spongiosa cornea.. This fluid per- 
forms the important office, of preserving the transparency of the 
cornea, by equably distending the cells, which may be proved by 
a simple experiment, viz. by forcing the fluid by pressure from a 
part of a recent cornea, when that part becomes opaque, but has 
its transparency restored by the return of the fluid, on the re- 
moval of the pressure. In old persons the cornea becomes 
denser in its structure, and often presents an opaque ring at its 
circumference, called Arcus Senilis. — 

The cornea is covered by the tunica conjunctiva, which ad- 
heres firmly to it, but may be separated after maceration. It 
can also be separated from the sclerotica after maceration, and 
a slight degree of putrefaction, especially if the parts, when in 
this situation, are suspended a short time in boiling water. 

The cornea is lined internally by a fine membrane, called the 
Capsule of the aqueous humour; which will be evident if the 
coats of the eye are boiled. In this case, the cornea hardens, 
and the capsule of the aqueous humour appears detached from 
it, like the cuticle raised by vesication. 

In a sound state, the sensibility of the cornea varies con- 
siderably.* The vessels in its structure do not carry red blood ; 

* It is the opinion of Dr. Physick, whose numerous und successful operations 
on the eye have afforded him many opportunities of judging, that the incision of 
the cornea always occasions some pain, which is very different, as to its intensity, 
in different persons. 

32 * 



378 CORNEA. 

it is, however, much changed in its structure by inflammation ; 
and it is said that blood has been found between its lamina, in 
consequence of violent strokes upon the eye. 

It is the segment of a smaller sphere than the sclerotica ; and 
therefore is more convex. The degree of convexity is very 
different in different persons; those in whom it is very great are 
necessarily short-sighted. It is not perfectly circular, but rather 
oval : the transverse diameter being the longest. 

The cornea and sclerotica are connected to each other by 
sloping surfaces. The edge of the sclerotica projects over the 
internal lamen of the cornea, and the edge of the cornea passes 
under the external surface of the sclerotica. 

The separation above mentioned proves the cornea and scle- 
rotica to be distinct from each other. And although their struc- 
ture is essentially different in the human species, it is much more 
so in some fishes and in some birds. 

— The cornea is about six lines in its longest or transverse 
diameter, and is a section of a spheroid, the diameter of which 
would be seven lines and a half. 

— Its thickness is nearly equal throughout ; about a line and a 
half. Mr. Ramsden and Sir E. Home assert, that it is rather 
thickest in the centre. On the inner face of the cornea, at its 
junction with the sclerotica, there is a slight groove, where the 
iris meets the ciliary ligament and is attached in contact with it. 
According to Professors Knox, Cloquet, and Jurine, the most 
internal layer of the cornea is united to the iris by short fibres, 
which have something of a tendinous appearance, and by which 
they think the contraction of the iris, augments the convexity of 
the cornea.* Ramsden and Home, assert that the tendons of 
the recti muscles are inserted into the layers, or rather expanded 

* Professor Jacob considers this internal layer of the cornea, (placed imme- 
diately in front of the aqueous humour,) as a peculiar layer of semicartilaginous 
matter, like the capsule of the lens ; the office of which is to preserve the proper 
curve of the cornea, and which he has named the elastic cornea. He considers it 
as terminating behind, by slipping in between the ciliary ligament and sclerotica. 
It is this membrane, he thinks, which forms the protruding pouch in ulcerations 
of the cornea. Dissections made in the manner he recommends, have not as yet 
proved to me, satisfactorily, its existence. — p. 



OF THE CHOROID. 379 

over the surface of the cornea; by the action of which the cornea 
may be flattened. This, however, is but a revival of the opinion 
of Morgagni and Briggs, which Zinn endeavoured to refute. — 

From what has been already stated, it appears that there are 
pores in the cornea, through which the fluid situated between 
its lamina may be pressed. 

It is probable that an exudation through these pores takes 
place after death, as a pellicle then forms on the cornea, which, 
upon examination, appears to originate from the drying of a 
fluid effused there. This has been considered as a proof of 
death; but there are few practical physicans who have not seen 
a similar pellicle, during life, in persons who were very weak. 

The Choroid Coat. 

The sclerotica and cornea compose a firm external shell for 
the eye ; upon which its form depends. 

The sclerotica is lined by a thin, flexible, very vascular mem- 
brane, denominated Choroides; which is in contact with it nearly 
throughout its whole extent. 

The choroides has been supposed to be derived from the pia 
mater ; but this sentiment is not confirmed by observation ; for 
the pia mater appears to be connected with the interior surface 
of the sclerotic coat. 

It is so delicate a membrane, and so vascular, that it has been 
considered by some anatomists as a texture composed entirely 
of vessels and nerves. 

It has three sets of arteries, which are derived from the oph- 
thalmic branch of the internal carotid, viz. 

1st. The long ciliary arteries, which are generally two in num- 
ber: they penetrate the sclerotic coat at the posterior part of the 
eye, and pass, one on each side of the external surface of the 
choroides, dividing at the ciliary circle, each into two branches, 
which inosculate with each other around the great circumference 
of the iris. 

— One of the long ciliary arteries {internal inferior) passes 
on the inner side, just below the horizontal diameter. The other 
{superior external) passes just above this diameter, on the outer 




380 VESSELS OF THE CHOROID. 

side. It is to avoid this vessel that, in operation for cataract, the 
needle is introduced a little below the horizontal level of the eye. 
The only arteries which are attended by veins, are the two long 
ciliary. These ciliary veins originate in the iris. The blood which 
is conveyed by the short ciliary arteries is returned, wholly by the 
venae vorticosae. — „. # 

2d. The short ciliary arteries, which &" J^ 

are very numerous : they penetrate 
the sclerotic coat near the optic nerve, 
are spread upon the choroides, and 
anastomose very frequently with each 
other: in their progress forwards they 
penetrate from the external to the 
internal surface of the choroides, 
and supply the iris and ciliary pro- 
cesses. 

— These are about twenty in number, where they perforate 
the sclerotica, but originate from the opthalmic as three or four 
separate branches. — 

3d. The anterior ciliary arteries, which are not very numer- 
ous, penetrate the sclerotic coat no great way behind the cornea. 
These are distributed among the branches of the long ciliary 
arteries on the iris. 

The veins of the choroides are very peculiar: besides those 
which accompany the arteries above described, there are several 
veins which are situated more internally than the arteries and 
nerves, and about the middle of the eye : their branches are not 
arranged in the usual manner, but run from the main trunk, nearly 
in a semicircular curve, are almost parallel to each other, and 
very numerous ; from this arrangement of their branches, they 
are called the Vasa Vorticosa. 

— There are, according to Zinn, four or five of these larger 
trunks, the branches of which are vorticose, or thrown into 

* Fig 75 is a representation of the vessels of the choroid coat and iris. The 
long ciliary artery and vein are seen running straight to the iris in front. The 
vasa vorticosa are seen upon either side. The short, ciliary arteries are not seen 
in this figure. — p. 



CILIARY NERVES. 381 



whirls, so as to admit of their arising from the whole surface of 
the choroid, in front, and behind, as well as upon the side of the 
trunks. 

— This arrangement, has an arborescent appearance, and has 
been compared to the weeping willow. The vorticose vessels, 
being compared to the graceful pendent branches of the tree. 
— These veins as well as the long ciliary, discharge finally at 
the back part of the eye into the ophthalmic veins or sinuses.* 
— The arteries that run to the ball are very flexuous and 
anastomosing, so that the impetus of the heart may be over- 
come, and the retina undisturbed by the pulsation of any of the 
vessels. The great vascularity of the choroid appears to be for 
the purpose of secreting the pigment in abundance, so as to ab- 
sorb the rays of light that enter from the pupil, and cut off those 
that penetrate on the side of the semi-opaque sclerotic coat. — 

The nerves which appear on the choroides, come from the 
ophthalmic ganglion : they pass very obliquely through the scle- 
rotica, and run forwards ; having a very flat appearance in pro- 
portion to their size: five or six of them are of this description ; 
some others are very small. There are some filaments which 
come from the nasal nerve, without passing through the ganglion. 

The internal surface of this coat is 
covered with a black paste, denomi- ' , S' '"• 

natcd Pigmentum Nigrum. This ap- 
pears to be spread most thickly on the 
anterior part of it, and thinner behind, 
near the optic nerve ; it is said to be 
thinner and less dark in old persons. 
It seems to resemble the matter of the 
rete mucosum of negroes, when that 
is softened by putrefaction. It is as- 
serted that the colour of this pigment 
has never been changed by the ordinary chemical agents, or by 
moderate heat. When it is washed away, the internal surface 
of the choroides appears to be villous.' 

* Zinn, De vasis Subtilior Oculi, 1790.— p. 

t A representation of the nerves of the choroid coat and the iris. — p. 




382 PIGMENTUM NIGRUM. 

There is also a portion of this substance on the external sur- 
face of the choroides. It is said that in very recent subjects, this 
matter appears to be inherent in the structure of the internal 
surface, and does not come off when it is rubbed gently ; or even 
when immersed in water ; but it is certain, that a considerable 
quantity of it sometimes appears on the exterior surface of the 
choroides, in eyes that are not very recent. 

— According to some experiments recently made by M. Mon- 
dini, and Professor Lavini, the dark-brown colour of this pigment, 
is owing to carbon and oxide of iron ; after incineration, parti- 
cles of iron were readily attracted from the remains by the mag- 
net.* 

— In the eyes of many animals, nearly all the ruminantia, the 
horse, the cetacea, most of the carnivora, and some cartilaginous 
fishes, the choroid presents at its back and lower part, a beautiful 
brilliant membranous appearance, which is called the tapetum hi- 
cidum, from its power of reflection. It supplies the place of pig- 
ment ; for underneath it the pigment is nearly or quite deficient. 
Its colour varies in different animals from greenish blue, to yel- 
low, and silvery white. 

— The rays of light in these animals, will therefore make a dou- 
ble impression upon the retina, as they pass through it to the 
choroid and outwards again by reflection. In man this tapetum 
does not exist, though the term is sometimes applied to the inner 
surface of the choroid. According to Dalrymple, the membrane 
of Jacob, is a double reflected serous membrane, one reflection 
of which is spread smoothly over the inner surface of the cho- 
roid in most animals, and seems to confine the pigment and pre- 
vent its staining the retina, and which, in maceration, breaks up 
and carries off the pigment in shreds. This appears to be the 
same membrane described by Mondini, (Membrana Mondini,) 
as ajjmagnificent and delicate net-work, with meshes so fine as to 
prevent the passage of a single globule of the pigment to sully 
in the least degree the delicate retina. Ruysch gave a descrip- 
tion of a membrane, since called the Membrana Ruyschiana, in 

* Anatomy of the Eye by J. Dalrymple, London, 1836. 



CILIARY LIGAMENT. ggg 

which he asserted that he had raised the inner vascular layer at 
the back part of the choroid where the final ramifications of the 
vessels take place, as a separate membrane : anatomists now 
generally consider this separation to have been artificial, and 
that the choroid is a simple vascular nervous membrane. — 

The celebrated Ruysch, and many anatomists after him, have 
considered the choroides as composed of two lamina; but it 
seems to be the opinion of the anatomists of the present day, 
that it consists of but one membrane ; and there are some who 
consider it as a mere tissue of vessels. 

In the white rabbit, and some other animals, the pigmentum 
nigrum is entirely deficient ; and the pupil of the eye appears of 
a red colour, owing to the blood-vessels of the choroides.* 

The general complexion between the choroides and sclerotica 
is very slight; depending upon a fine cellular substance, and very 
small blood-vessels and nerves. 

But immediately around the margin of the cornea, the cho- 
roides and sclerotica are firmly connected to each other, by the 
intervention of a portion of cellular substance, which although 
soft, is dense and compact, and of some thickness. As this sub- 
stance extends round the circumference of the cornea, it neces- 
sarily forms a ring; which is between one and two lines broad. 
This substance, thus placed, constitutes the Ciliary ligament; 
which has, to the great perplexity of students, been called by 
many different names; as Orbicularis Ciliaris, Annulus ganglifor- 
mis, &c.f 

It is very distinguishable from the choroides, the sclerotica, and 
the iris; and appears generally of a gray colour; but contains 
the ciliary nerves and arteries, in great numbers, as they pass to 
the iris. 

In this circular band is a small canal, discovered by the Abbs 
Fontana, which is moistened by a pellucid fluid ; but its use is not 
known.J 

* Its deficiency is also observed in individuals of the human race, called Albi- 
nocs or leucrethcopics. — p. 

* Discovered by Fallopius in 1584. 

tSee Fontana on the Poison of the Viper, vol. 2, page 310; and also Adolph 
Murray, Nova Acta Upsal, vol. 3. 



384 



THE IRIS. 



All the choroides, which is posterior to the ciliary ligament, is 
in close contact with the internal surface of the sclerotica ; but 
the choroides continues anterior to the ligament; and this ante- 
rior portion takes a different position. It no longer lines the in- 
ternal surface of the shell of the eye; but is reflected inwards; 
and takes a transverse direction, as if it were to form a partition. 
This reflected part forms the ciliary body, and the ciliary pro- 
cesses, which will soon be described. 

The choroides begins to take this reflection inwards, at the 
place where it is connected with the ciliary ligament. Immedi- 
ately anterior to the ligament, the cornea is continued from the 
sclerotica, and, being more convex than the sclerotica, it pro- 
jects externally and anteriorly. As the ciliary ligament is situ- 
ated between the sclerotica and choroides, very near to the place 
where the sclerotica unites to the cornea, and where the cho- 
roides is reflected internally to form the ciliary processes, the 
edge of the ciliary ligament must lie in the angle formed by the 
cornea, which is anterior and external, and the reflection of the 
choroides, which is internal. To this edge of the ciliary liga- 
ment is fixed the circumference of the circular membrane, called 
Iris, which is now to be described. 

The Iris 

Is a flat membrane, which does not partake of the spherical 
figure of the sclerotica and cornea, or of the choroides, but ex- 
tends across a portion of the cavity of the eye, and forms a sep- 
tum. As it is circumscribed by the ciliary ligament, it is neces- 
sarily circular. It has a round foramen near its centre, which is 
called the Pupil, which, in the healthy subject, varies continually 
in size, according to the degree of light to which the eye is 
exposed.* 

The situation of the iris in the cavity of the eye is such, that, 
at its circumference, it is nearly in contact with the circumfer- 
ence of the cornea ; it is actually in contact with the anterior 

* The iris is rather narrower next the nose, than on the side of the temple, by 
which reason, the pupil is not exactly in the centre, as first stated by Winslow in 
1711.— p. 



IRIS. 



385 



edge of the ciliary ligament, and with the anterior surface of 
that part of the tunica choroides, which is reflected inwards, and 
forms the ciliary processes. 

As the iris is flat or plane, and the cornea is the segment of a 
sphere, there must be a considerable vacuity between them. 
This vacuity constitutes the anterior chamber of the eye. 

The iris, therefore, is a septum, passing across the eye at its 
anterior part, and separating that portion of the cavity, which is 
bounded exteriorly by the cornea, from the larger portion formed 
by the sclerotica. 

The anterior, or external surface of this membrane, is very 
remarkable for its colour ; in persons of a light complexion it is 
generally of a light blue, intermixed with white; or of a gray, 
or light hazel, &c. In those whose complexions are dark, it is 
almost invariably dark also. These colours are so arranged, that 
frequently there is an appearance of lines, sometimes nearly ra- 
diated, more frequently curved in various directions, but tending 
from the circumference towards the pupil or centre ; and when 
the general colour of the iris is blue, these lines are often 
whitish. 

When this surface is examined in water with a magnifying 
glass, it appears to be covered with very fine villi, which pro- 
bably have the effect of increasing its lustre. 

From a supposed resemblance of these colours to those of the 
rainbow, the membrane has been called Iris, and is generally 
known by this name; but, unfortunately, another appellation has 
been given to its internal and posterior surface, which is covered 
with a black pigment like the choroides, and has been commonly 
called Uvea.* 

This black pigment, on the internal or posterior surface of the 
iris, has been supposed to have a great effect in determining its 
general colour; and there is some reason for this opinion, as the 

* So called from its colour, which is dark brown, resembling the skin of a raisin. 
The inherent colour of the iris is either light blue or orange, which, with the pig. 
njent on its back part that varies in thickness and in intensity of die in different 
subjects, form all the variety of colours of the human eye. — P. 

vol. II. 33 



ggg STRUCTURE OF THE IRIS. 

iris is partly transparent ; but there is a colour inherent in it, 
which is most evident when the black pigment is very carefully 
washed away.* 

Thus, the light hazel colour remains unchanged after the black 
pigment is removed ; and it is not probable that light blue is 
much influenced by the black pigment. 

The iris is capable of dilatation and contraction to a very 
considerable degree, by which the pupil, or central vacuity is 
enlarged or diminished. By this means it regulates the quantity 
of light admitted into the eye. Upon the first exposure to 
strong light, the pupil of every healthy person is observed 
to be diminished, and upon the diminution of light, to be 
enlarged. 

It has been ascertained by experiment, that this motion of the 
iris is not excited by the action of light immediately upon it, but 
on the interior surface of the eye ; and this circumstance has 
occasioned the greatest attention to the structure of this extra- 
ordinary and important membrane. 

Anatomists of the greatest respectability hold opinions ex- 
tremely different, indeed, respecting the structure of the iris. 
They agree that there are many radiated fibres on the posterior 
surface, commencing at its circumference, which can be readily 
seen when the black pigment is washed away ; but while many 
respectable anatomists declare that they have not been able to 
see any circular fibres, Dr. Monro describes them minutely, and 
has published a plate of them. He considers them as forming a 
circle immediately round the pupil, which circle makes about 
one-fifth part of the breadth of the iris.f 

In the human subject, the iris does not appear to be divisible 

* Sometimes the pigment is strewed here and there in patches, thicker than in 
other parts, which gives a marbled appearance to the iris. The pigment, which, 
like that of the choroid coat, is a secretion from the vessels of the part, is con- 
fined by having reflected over it, the serous membrane of the posterior chamber of 
the eye. — p. 

t See his publication, entitled Three Treatises : On the Brain, the Eye, and the 
Ear. 



ACTION OF THE IRIS. 397 

into lamina.* It is abundantly supplied with arteries, which form 
two circles upon it, and it has also a large supply of nerves. 

The operations of the iris, in contracting the pupil, upon 
exposure to light, and dilating it, when light is diminished or 
withdrawn, have been explained very differently by persons 
who have different sentiments respecting its structure. Some 
of those persons, who do not believe in the existence of mus- 
cular fibres in the iris, suppose its motions to depend upon the 
sudden turgescence or depletion of its blood-vessels : while others 
impute it to a peculiar quality, exclusively enjoyed by this mem- 
brane. 

Dr. Monro, who refers the contraction of the pupil to the 
action of the circular fibres, which is excited by the stimulus of 
light applied to the retina, considers this operation as analogous to 
that of the abdominal muscles, in those cases of coughing, which 
are produced by irritation of the glottis. The action of the 
muscles, in these instances, being excited by substances applied 
to the glottis, which would have produced no irritation if they 
had been applied to the muscles themselves. 

The dilatation of the pupil appears, in the human species, if 
not in other animals, to depend upon a different cause. It seems 
to be a passive state of the eye, which takes place when the sti- 
mulus is withdrawn, and the consequent action ceases. There 
is some elasticity in the iris; and a great many, perhaps all, of 
its natural or healthy motions in the human species, may be ex- 
plained by the contraction of the circular fibres, induced by 
irritation : and by the contraction of the rest of the membrane 
in consequence of its elasticity ; which always exhibits its effects 
when the muscular action ceases. 

— It is a question yet undecided, whether the contraction and 
dilatation of the pupil is dependent upon an involuntary sphincter 
muscle, placed at the pupillary margin, and a series of longitu- 
dinal or radiated fibres, running from the greater to the lesser 

* According to H. Cloquet, - the iris consists of two lamina, intimately united 
near the pupil, but separable towards the greatest circumference. It is, besides, 
lined, in front and behind with the transparent serous membrane of the aqueous 
chambers. — p. 



388 



JACOB, ON THE MUSCULAR STRUCTURE OF THE IRIS. 



circumference of the iris, as asserted by Monro, and more re- 
cently still, by Professor Maunoir and others, or whether it is 
simply an erectile tissue, dependent in its contraction upon a rush 
of blood, under the influence of some stimulation, into its serpen- 
tine vessels. Anatomists of nearly equal reputation, advocate 
these opposite theories. Small doses of belladonna, stramonium, 
or opium, dilate the pupil ; larger and poisonous doses, contract it. 
The motions of the iris, contracting to diminish the quantity of 
light admitted, when the rays excite too intense an impression on 
the retina, and dilating to receive more when they are feeble, 
appear, in many respects, like muscular action, and have been 
compared to the heart, dilating to receive blood, and contracting 
to expel it. Professor Jacob, of Dublin,* describes the circular 
muscle as very visible, in some quadrupeds, after the pigment 
has been removed, on the back surface of the iris, near the pu- 
pillary margin, and is about the twentieth part of an inch in di- 

_. , ameter. The longitudinal or 

r IS". T7 t • • . 

dilating fibres, he has described 
on the front of the iris, as con- 
sisting of irregular shaped 
masses, placed in the middle 
space between the greater cir- 
cumference and the pupil, send- 
ing forward a number of little 
elevated lines or tendons which 
terminate in loops about the 
twentieth part of an inch from 
the pupil, and from these loops 
smaller striae converge to the 
edge of the central opening. 
The whole arrangement, he says, is like that of the columnce 
carnece and chordce tcndinecE of the heart. The examination of 
a hazel eye, in a living subject, or of an iris, under water, seems 




* Medico-Chirurgical Transactions. 

t Fig. 77, is a very accurate representation, according to Professor Jacob, of 
the face of the iris, showing the columnar carneae and chord^e tendineae much 
magnified. The posterior surface of the iris presents a very different appearance. — p. 



ORGANISATION OF THE IRIS. g§9 

in favour of his views. The iris is extremely vascular, and re- 
ceives its blood partly from the long, and partly from the ante- 
rior ciliary arteries. 

— They anastomose with each other, so as to form the greater 
arterial circle round the outer margin of the iris, and then run 
out in a serpentine course and form a lesser circle near the pu- 
pillary margin. From this lesser circle, innumerable minute ves- 
sels radiate toward the centre, and abruptly terminate at the edge 
of the pupil. When the pupil is contracted to its minimum size, 
these vessels become straight. The veins are also abundant; 
some terminate in the long ciliary veins, and some in the vasa 
vorticosa. 

— With nerves also, the iris is richly furnished, probably more 
abundantly than any other tissue of equal size in the whole eco- 
nomy. It is supplied from the ciliary nerves, which run out 
between the choroid and sclerotica, in the form of flattened 
cords, after they have perforated obliquely the latter tunic. 
— They inosculate with each other frequently in the greater ar- 
terial circle of the iris, and appear under the microscope to form 
little knots or ganglia ; the branches which they send inwards 
towards the pupil, may be seen in some of the larger quadrupeds 
to inosculate with each other, but cannot be traced satisfactorily 
on account of their faint appearance a'nd pulpy character. — 

The elastic power in this case may have some analogy to the 
elasticity of the arteries, which certainly produces some of the 
contraction of those vessels ; but there is another principle of 
contraction superadded to this, which produces effects different 
from those of mere elasticity.* 

In the foetus, prior to the seventh month after conception, the 
pupil is closed by a delicate vascular membrane, called the 
Membrana Pupillaris ; which, after this period, completely dis- 
appears.! 

— The membrana pupillaris as shown, by W. Hunter and J. 

* Some persons, like the late Dr. Wollaston, exercise a voluntary control over 
the movements of the iris, dilating or contracting it at will. — p. 

t The discovery of the Membrana Pupillaris is claimed by Wachendorf, Prof. 

33* 



t 



390 ME.MCKA.VA PUPILLARIS. 

Cloquet, consists of two layers, formed by an extension, back to 
back, of the serous lining membrane of the anterior and posterior 
aqueous chambers, across the pupil. This is ruptured, or effaced 
by a retraction of its vessels, to form the lesser arterial circle of 
the iris,* which is never seen till after the removal of the mem- 
brane. The lining membrane of the two chambers then form a 
continuous coat. — 

The iris was formerly supposed to be a continuation of the 
choroid coat; but it is now generally agreed that it is a distinct 
membrane ; for when the eye is very slightly affected by putre- 
faction, it can be pulled off, and the choroides left entire. 

The choroides, on the contrary, cannot be separated from the 
ciliary processes without laceration ; and when the pigment is 
washed away from its internal surface, it is very obvious that 
these processes are continued from the substance of the cho- 
roides and reflected inwards, so as form a projection into the 
cavity of the eye. 

Of the Ciliary body, and the Ciliary Processes. 

This internal projection forms a ring or a circle, which has 
the ciliary ligament before described, near its circumference, 
and anterior to it.f 

It is so disposed, that the whole of its internal or posterior 
surface appears to be formed into radiated plaits, which extend 

of Botany in the University of Utrecht; by John Hunter; by Halle r ; and by 
Albinus. 

* The thickness of the iris, is considered three or four times as great as that of 
the choroid. When the pigment is carefully wiped away from the posterior surface 
of the iris, we see, according to H. Cloquet, a great number of straight, raised, and 
converging lines, which are confounded into a membranous zone near the pupil, 
and appear to be the continuation of the ciliary processes. Well marked villi are 
also seen on the posterior surface. — p. 

t The ciliary ligament or circle, evidently serves as an attaching medium be- 
tween the iris, cornea, and sclerotica. Its structure is not fully understood. Some 
modern anatomists, have considered it in the light of a nervous ganglion; others as 
composed of muscular fibres. Vide, Knox on the Muscularity of the Ciliary Liga- 
ment. Ed. Philos. Trans, vol. x. — p. 



CILIARY BODY AND CILIARY PROCESSES. 39 J 

from the circumference to the central vacuity, where they ter- 
minate. 

The whole of this structure, or the membrane thus plaited, is 
called the ciliary body, while the plaits are called the ciliary 
'processes. 

In a natural state of the eye, the ciliary body is covered with 
a large portion of the pigmentum nigrum. It may be seen very 
well by placing the eye on the cornea and removing the posterior 
part of all the coats, without deranging the humours. When 
thus viewed from behind, it has a black surface, and appears like 
a ring formed of radiated lines ; it has been compared to a flower 
with radiated petals. 

When the black paint is washed off, and the humours of the 
eye removed with proper caution, the plaited structure of these 
radiated processes will be very apparent; it then will appear that 
the membrane of the choroides is so arranged as to form radiated 
plaits, and that these plaits are the ciliary processes. 

These plaits or processes do not lie upon each other, but are 
placed on their edges, one edge looking into the cavity of the eye, 
and the other edge anteriorly towards the iris. 

Each ciliary process seems to originate from two lines or 
smaller plaits, called the ciliary slrice, which soon unite and form 
it. The process or plait, thus formed, is rather larger at its cen- 
tral extremity than at any other part; and their central extremi- 
ties are not of equal lengths, but alternately longer and shorter. 

The ciliary processes do not extend to the centre of the circle 
of which they are radii, but stop short of it ; and thus include a 
circular vacuity or aperture, which is larger than the pupil of 
the iris, and situated a little way within or behind it. This 
aperture is occupied by the crystalline lens (to be hereafter de- 
scribed) ; but the central extremities or terminations of the cili- 
ary processes do not adhere to the lens, for they are loose and 
movable; but they are in contact with its anterior surface, near 
the margin. 

It is, however, to be observed that the ciliary processes are 
loose only at their central extremities; for, towards their other 
extremities, they seem to adhere, anteriorly, to the iris; and, 



392 



CILIARY PROCESSES. 




posteriorly, to the retina, and to the capsule of the vitreous 
humour. 

— The ciliary processes 
vary in number from 70 to 
85. They are extremely 
vascular and when mi- 
nutely injected and mag- 
nified, their vessels present 
the appearance of the ner- 
vuresor vessels of a willow 
leaf. Their intimate struc- 
ture and function are un- 
known. Home, Wal- 
lace* and others from their 
observations on the infe- 
rior animals, believe them 
to be muscular and to aid in adjusting the focal distance of the 
lens, to the capsule of which they are indirectly connected ; draw- 
ing it backwards and forwards like a magnifying glass, with 80 
strings attached to its margin.f Others, with equal reason have 
believed them to be erectile, altering the position of the lens by 
their expansion or contraction. The processes are not of equal 
length, each alternate one being shorter. Fishes with spherical 
lenses, according to Mr. Wallace, have no ciliary processes : 
The adjustment of the lens being in them effected by a single 
membrane or muscle attached at one point. The rolling of the 
lens, as it is drawn backwards, it being a sphere, can make no 
difference in regard to its functions. — 

The ciliary body, (or the radiated ring formed by all the pro- 
cesses) is about two lines broad in the human subject ; but the 
part next to the nose is rather narrower than the rest of it. 
The black pigment is spread over the whole of the posterior, 



* Structure of the Eye, by W. C. Wallace. New York, 1836. 

t This figure from Zinn's work, represents the corpus ciliare or circle of ciliary 
processes in man, on a large scale. In the centre is seen the iris, with its pupil- 
lary opening. There is certainly no direct connexion, between the central extre- 
mities of the ciliary processes and the capsule of the lens. — p. 



RETINA. 393 

or internal surface, of the ciliary body; but it is much more abun- 
dant towards the circumference than towards the centre. It is 
also more abundant in the furrows between the ciliary processes 
than it is in the processes themselves; and as the membrane, of 
which the processes or plaits are formed, is of a whitish colour, 
the processes, at their central extremities, have a whitish cast. 

The black pigment is also spread over the anterior surfaces of 
the processes; on all that part which is loose, and not in contact 
with the posterior surface of the iris. 

When the pigment is completely washed away, the colour of 
the ciliary body appears grayish; but if the eye has been suc- 
cessfully injected, it will appear to be composed almost entirely 
of vessels; and to have a villous surface. 

The Retina. 

Within the tunica choroides, and in contact with its internal 
surface, is a third coat of the eye, the Retina. This coat is evi- 
dently derived from the optic nerve, although its texture appears 
somewhat different. 

Before the optic nerve arrives at the ball of the eye, a small 
branch of the ophthalmic artery penetrates its coats; and when 
the nerve perforates the tunica sclerotica, as described in page 
375, this artery passes with it. 

On the internal surface of the choroides, the nerve forms a 
small prominence; and from this, the retina expands, with many 
ramifications of the aforesaid artery in it. 

The retina has the appearance of mucus, and the semi-trans- 
parency of a surface of ground glass; but when immersed in 
water, it floats like a membrane. 

By particular management, when the retina floats in water, a 
considerable quantity of the soft substance may be removed, and 
a delicate, soft, transparent, membranous substance, with the 
vessels, will remain. 

The retina, therefore, seems to consist of a delicate, vascular, 
membranous web, with a medullary pulpy matter spread upon it, 
and supported by it. 



394 0F THE RETINA. 

Thus constituted, the retina extends from its origin, at the 
optic nerve, to the commencement of the ciliary processes. 

It lines the choroid coat, and is, therefore, in contact with the 
pigmentum nigrum, on its internal surface, but it is simply in con- 
tact with it, and is not tinged by it. No vessels pass from it to 
the choroides; and, when a posterior section of the eye is made, 
it slips from it without any appearance of adhesion, being at- 
tached only to the optic nerve. 

Most anatomists agree respecting these circumstances, but 
there is the greatest difference of opinion respecting the extent of 
the retina. Several distinguished anatomists, of the last century, 
thought very differently from each other on this subject; and two 
of the first anatomists of the present day have embraced opinions 
entirely opposite. Monro is convinced that it extends, under 
the ciliary processes, to the crystalline lens: and Sommering 
asserts, positively, that it terminates at the commencement of the 
ciliary processes.* Some of the anatomistsf of London, incline 
to the opinion embraced by Sommering; and the late ingenious 
Bichat adopted the opinion embraced by Monro. 

Both parties confide in their own observations, and refer to the 
eye. An object which appears so very different to different per- 
sons, who have good sight, cannot be very distinct. The pulpy 
substance of the retina appears to terminate at the commence- 
ment of the ciliary processes; but a membrane of a very differ- 
ent texture seems continued from it to the crystalline lens. 

Although the eye and the retina have long been objects of ana- 
tomical attention, Professor Sommering made an interesting 
discovery respecting it, so lately as the year 1791, viz. that, at 
the posterior part of the retina, in the axis of the eye, and, of 
course, a little exterior to the entrance of the optic nerve, there 
is a spot of a circular or oval figure, about one line, or rather 
more, in diameter, of a yellowish or saffron colour, which is 
brightest about the centra. 

* This opinion of Sommering', which was advocated by Zinn and Morgagni, 
and more recently by Meckel, is now generally admitted. By careful observation it 
may be seen terminating a short distance behind the ciliary body. — p. 

t See the new Cyclopaedia, by Dr. Fees and others, article Eye. 



SPOT OF SOMMERING. 



395 



In the centre of this spot is a round hole, equal in diameter to 
one-fourth of the spot. There are, generally, several small plaits 
of the retina about this place; one of these, which is very con- 
stant, extends from the optic nerve to this spot. 

The colour of this spot is pale in children, bright in young 
persons of mature age, and pale at an advanced period of life. 

The foramen is to be found in the fetus, but not the yellow 
spot. The colour of the spot diminishes when vision is ob- 
structed; and the spot disappears when vision is lost. 

There is the greatest 

Fip 79 * 
reason to believe that 

the retina is the seat of 
vision; but it has been 
ascertained, most deci- 
sively, that the extre- 
mity of the optic nerve, 
from which the retina 
originates, is insensible 
to the rays of light. 

— Professor Knox of 
Edinburgh, and J. Dal- 
rymple, from many careful observations made upon the subject, 
consider the folds of So nmering, as entirely a post mortem ap- 
pearance, dependent on a collapsing of the retina, consequent to 
the escape of the fluids, through the cornea, which takes place 
speedily after death. This corresponds with my own observa- 
tion, made upon the eye of a convict within three hours after 
execution, in company with Dr. J. K. Mitchell of this city, and 
the late Dr. J. P. Hopkinson. In this case the yellow spot of 
Sommering was very manifest, and about two lines in diame- 
ter; but the surface of the retina was perfectly plain, and the 

* Fig. 79 represents the retina, to which the optic nerve is attached behind, ex- 
panded in the form of an incomplete sphere over the hyaloid membrane of the 
vitreous humour, and terminating in front a short distance from the lens. The 
lensisscen lodged with its capsule, in a depression on the front of the vitreous hu- 
mour, and surrounded by a series of delicate folds, (zona ciliaris,) which correspond 
with the ciliary folds of the choroid, (see Fig. 78.) The spot of Sommering is seen 
near the entrance of the optic nerve. — p. 




396 AMMON ON THE SPOT OF SOMMERING. 

foramen appeared to be but a superficial depression, the size of a 
small pin's head, with a slightly elevated brilliant yellow margin. 
Dalrymple observed in one case the surface of the retina, per- 
fectly smooth, and as the fluid escaped, the circular edges of the 
cup-like depression, (which he with Meckel and others, consider 
the foramen of Sommering merely to be,) were elongated, ele- 
vated, and finally came in contact, forming the fold of Sommer- 
ing. 

— According to Ammon, who has written a work, ex-prof esso, upon 
the yellow spot of Sommering, there is never at any period of life 
to be found the foramen of which Sommering speaks. The de- 
pression on the surface of the retina, and the appearance of a fora- 
men are owing to the more intimate union at this point, of the cho- 
roid and retina by the intermedium of vessels. The yellow spot, 
according to him, is very vascular, and is usually apparent fourteen 
or fifteen months after birth, and is always to be found in the 
healthy adult eye. He has twice sought for it in vain, in cases of 
amaurosis, and once in congenita] cataract. In the early periods 
of foetal life, the choroid is red, and contains no black pigment. 
— After the pigment is deposited, and toward the period of birth, 
its colour in the axis of the eye, where the yellow spot is to appear, 
is of a lighter brown than in other parts. As the spot begins to 
make its appearance fourteen or fifteen months after birth, the 
yellowness is first obvious on the outer side of the retina, next to 
the choroid, and he believes is entirely dependent on the action 
of light upon the retinal surface of the choroid pigment. 
— The pigment, diluted with water, and exposed to the action of 
the rays of the sun, he says assumed a yellowish appearance. 
Inflammation of the eye, he asserts may produce the same change, 
as seen especially in the uvea, in inflammation of the iris, around 
the pupillary margin, where is formed the brown circle of which 
Lawrence speaks.* In the early state of developement of the foetal 
eye, be found the sclerotica and choroid protuberant inward, 
opposite the place where is subsequently formed the yellow spot, 
and at which spot penetrate some of the ciliary arteries that 
subsequently branch from thence into the retina. The appearance 

* Vide Lawrence, on the Venereal Diseases of the Eje. 



RETINA. 397 

of the black spot or foramen of Sommering, he believes to be 
caused by a rupture of the delicate retina at this point, bringing 
into view the black pigment on the face of the choroid. In its 
first stage of formation the retina appeared a transparent layer, 
readily separated both from the choroid and the optic nerve. 
— The use of the yellow spot, which he considers the most sensi- 
tive part of the eye, is to give a common axis to the organ, and 
stability during the exercise of vision. Hence the vacillation of 
the balls, and occasional squinting common to young infants prior 
to the formation of the yellow spot, as well as the rolling of the 
balls, in congenital cataract. 

— " Centrum retinas, in quo macula flava occurrit, prae caeteris 
ejus partibus lucis assimilationi optum esse videtur; necessario 
incfe sequitior, puncretinge locum imprimis lucis radiis offici et 
quasi detineri, non potest igitur non uterque oculus uno eodum- 
que dirigi motu, et uno quasi stabiliri axe. Normalis autem 
haec oculi conditioni tunc desideratur, cum macula lutea non- 
dum formata est, sive cum suspicari licet, hujus organi genesin 
prohibatum, aut ejus oeconomiam turbatum esse." 
— It is from this part, also, he thinks, originate those various ex- 
pressions of the eye indicative of certain states of mind, as pity, 
hatred, love, sadness, etc. ; while from the eyes of animals, es- 
pecially those with the tapetum, there is emitted only the corrus- 
cations, indicative of rage.* 

— In the human eye, the external medullary pulpy layer of the 
retina, when beaten up, presents all the appearance of central 
matter, as was observed by Galen. The nervous matter is, how- 
ever, arranged in the form of fibres, agreeably to the recent mi- 
croscopical observations of Langenbeck and Treviranus. Ac- 
cording to the latter, when the optic nerve has penetrated through 
the sclerotic and choroid to the retina, its cylinders or nervous 
tubes spread themselves out on every side, either singly or col- 
lectively, into bundles ; each cylinder, or collection of tubes bend- 
ing inwards through the vascular layer, and terminating in the 
form of a papilla on the surface of the vitreous humour. In the 

* Fred. Aug. ab Ammon, de Gcnesi et usu maculae luteae, in retina oculi hu- 
mani obvioe. Accedit tabulae in aes incisa. — Vinarias, 1830. 
vol. ii. 34 



398 VASCULARITY OP THE RETINA. 

eye of the halibut, the fibrous structure of the retina appears very 
manifest. 

— Considering the formation of the retina, as described by Am- 
nion, its great sensibility to light, and the known insensibility of 
the optic nerve to that stimulus, if the rays fall on it in any part 
of its course without firstimpinging on the retina, the retina can- 
not be considered as a mere expansion of the optic nerve, any 
more than the nerves themselves can be considered as a mere 
expansion of the brain. The retina may be considered as a pe- 
culiar structure, for the purpose of receiving the impression of 
the rays of light; the nerve as the mere agent by which this im- 
pression is transmitted to the brain, where it becomes a sensation. 

Vascularity of the Retina. 

— It receives its supply of blood principally from the arteria 
centralis retinae of Zinn, a branch of the ophthalmic, which enters 
the optic nerve a short distance from the ball, and passes through 
the central foramen in the cribriform plate of Albinus, vide p. 375. 
— Its distribution is principally to the internal vascular layer of 
the retina, and in the healthy state contains only the white por- 
tion of the blood. The blood is returned in veins which terminate 
in a single trunk that passes out through the cribriform plate. — 
[Within three or four years a membrane has been discovered 
by Mr. Jacobs, Demonstrator of Anatomy in Trinity College, 
Dublin, which is situated between the retina and the tunica cho- 
roidea. Its tenuity and delicacy are extreme. It is diaphanous 
and is thought by its discoverer to be a serous membrane. It 
extends from the optic nerve as far forwards as the retina goes, 
and adheres by a delicate filamentous structure to both the retina 
and the choroid coat, but much more firmly to the former. Mr. 
Jacobs asserts that this filamentous structure, by which it adheres 
to the other two coats, is vascular: as this assertion, however, is 
founded on a process of reasoning, and not on absolute demon- 
stration, our assent may very properly be withheld from it till an 
injection is brought forward to prove the fact. This membrane 
is well marked also in the sheep, ox, horse, dog, and other do- 
mestic animals; indeed, in all the mammalia which he has had 
the opportunity of examining. It exists, also, in birds and fishes, 



TUNICA JACOBI. 399 

and is said to be particularly strong in the latter. M. Cuvier has 
described it in fish as one of the lamina of the retina, but its sen- 
sible properties are asserted by Mr. Jacobs to be very dissimilar 
to those of the retina. 

As this membrane may possibly be confounded by the student 
with one of the lamina of the human retina, it should be borne 
in mind that the latter consists of two parts, a pulpy or nervous 
expansion and a reticulated vascular structure on which the pulp 
is laid, the pulpy part being external. 

The reticulated structure is called by some the tunica vascu- 
losa retinae. Most anatomists have known and admitted these 
two membranes as composing the retina, yet but few have had 
the expertness to separate them from each other, and to leave at 
the same time the membranous structure visible. Albinus had 
the success to accomplish this separation; and I am informed, 
on the authority of Dr. Physick, that Mr. Hunter also succeeded 
in it. 

When the common dissection of the retina is made and fixed 
in clear water, this membrane will be seen floating around it in 
delicate flocculi; but if a more careful dissection be made, by 
fixing the eye to the bottom of a basin of water, by its cornea, 
through the aid of shoemaker's wax, and the sclerotica and cho- 
riodea be removed from behind, this membrane may be turned 
down entire from the retina, with the end of the handle of a 
scalpel.] 

— Fig. 80, represents on Fig. 80. 

the left, the retina, with a 4k 
portion of the optic nerve fj 
attached to it. The exter- 
nal membrane (tunica Ja- 
cobi) is turned down, and 
the foramen of Sommer- 
ing instead of a distinct 
hole, presents the appearance of a fold or depression with ele- 
vated sides. The figure to the right, shows the retina expanded 
over the vitreous humour, and the place may be observed from 
which the optic nerve has been cut away, and from which 




400 VITREOUS HUMOUR. 

the vessels branch out. To the left of this is seen the foramen 
of Sommering, represented as a black spot, surrounded by a dark 
shade. — 

Of the Humours of the Eye. 

The three humours of the eye, viz. the Aqueous, the Crystalline, 
and the Vitreous, are separately invested with a membranous 
capsule, which is very delicate, and perfectly transparent. 

The Vitreous Humour 

Occupies almost all the cavity of the eye which is posterior 
to the iris. It of course possesses a spherical form. It has a 
depression in the centre of its anterior surface, in which the pos- 
terior surface of the crystalline lens is received. It is covered 
by the retina as far as the retina extends. 

The peculiar consistence of this body, which resembles that of 
melted glass, is owing to its membrane; which is a spherical 
sac, divided by many septa, or partitions, that form small irre- 
gular cavities, in which a fluid is contained. This membranous 
sac is most perfectly transparent, and very flexible ; it has, how- 
ever, some strength; as it will support the weight of all the fluid 
it contains, and may be suspended from a hook or forceps. The 
fluid may be separated from the membranes, by beating the 
vitreous humour in a cup with a spoon; or by suspending the 
vitreous humour, and then puncturing it. In either case the fluid 
escapes ; but the internal arrangement of the membranes is not 
visible. 

It is said that when this body is frozen, the portions of fluid 
in the different cavities, have sometimes been distinguishable 
from each other, as distinct pieces of ice; and that their form is 
that of small wedges, with their edges directed to the crystalline 
lens as a centre, and their bases to the circumference of the vi- 
treous humour. It is also said, that if this body be immersed in 
a solution of potash, the membranes will become opaque, while 
the fluid continues transparent; and that the appearance of the 
cells, thus exhibited, agrees with the form of the pieces of ice 
above mentioned. 



TUNICA HYALOIDEA. 401 

This membrane is now generally called the Tunica Hyaloidea, 
from two Greek words which imply a resemblance to glass.* 

Its particular structure is not perfectly understood. Vessels 
are not generally seen on it in the adult; but, in the foetus, the 
artery in the optic nerve, (or the central artery,) sends a branch 
through the vitreous humour to the crystalline lens ; and some 
branches of this artery are to be seen on the tunica hyaloidea.f 

Throughout the greatest part of its extent, it appears to con- 
sist of but one lamen ; but at the front part, near the ciliary pro- 
cesses, there are two lamina. The internal, or posterior, seems 
to be a portion of the proper tunica hyaloidea, and passes behind 
the crystalline lens. The external, or anterior, passes over and 
before the lens; or at least is attached to the anterior part of the 
capsule, in which the lens is contained. It is supposed, by some 
anatomists, that this membrane is continued completely over the 
crystalline lens; but it has not been separated. 

As this lamen extends round the crystalline lens, it is in con- 
tact with the ciliary processes; or, with a production from the 
retina, which is supposed by some anatomists to pass between 
them. It is impressed with radiated plates by the ciliary pro- 
cesses, and some of the pigmentum nigrum of these processes ad- 
heres to it. 

As these lamina of the tunica hyaloidea are separated by the 
crystalline lens, there is a vacuity between them, around the 
margin of the lens, and this vacuity must necessarily be circular 
in its course. 

It is not probable that any considerable quantity of fluid is 
contained in this vacuity ; for the two lamina concerned in its 
formation, appear in contact with each other. It can be readily 
demonstrated by puncturing the external lamen, and blowing 
into it through a small pipe. When thus distended, there appear 

* Discovered by Fallopius in 1584. 

+ It is also believed that vessels pass from the ciliary processes of the choroid, 
to the ciliary folds (zona ciliaris) of the hyaloid tunic, between which the choroid 
processes are embedded. The hyaloid tunic must be very vascular, though usually 
containing only white blood, for in calves and sheep driven with blows to the sham- 
bles, the vitreous humour is often tinged with blood. — p. 

34* 



402 



CANAL OF PETIT. 



to be incomplete partitions in the canal, or partial adhesions of 
the lamina forming it, which have the effect of partitions; these 
partitions are placed in a radiated direction, at some distance 
from each other, and give the canal a peculiar indented appear- 
ance. It is called by the name of the celebrated Petit who dis- 
covered it. 

The anterior lamen of the tunica hyaloidea, which forms part 
of this canal, seems to adhere to the coats of the ciliary pro- 
cesses; for, if a section is made behind the ciliary ligament of 
all the coats of the eye, the vitreous humour will be found ad- 
hering to the anterior portion of the section, when it is lifted up. 
Fig. 81. — Fig. 81, is an enlarged repre- 

sentation of the canal of Petit (call- 
ed godronnt, from its resemblance 
to the puckers or ornaments of sil- 
ver plate.) The lens is seen inclosed 
in its capsule, over which the ante- 
rior layer of the hyaloid is believed 
to pass. On the outer side is seen 
the canal of Petit; and on the outer 
side of this again, the corona, or 
zonula ciliaris of Camper and 
Zinn, stained by the pigment, and in the folds of which are placed 
the ciliary processes. The two bodies are thus, as it were, dove- 
tailed together, and vessels, according to Dr. Knox, pass from 
the latter to the former. 

— The zona, or corona ciliaris of Camper and Zinn, may be seen 
very distinctly by removing the sclerotica, choroid, iris, and re- 
Fig - . 82. tma ' one or tw0 days a f ter death, leav- 
ing the vitreous humour entire, with the 
lens embedded in its anterior part. We 
then perceive a number of striae on the 
vitreous humour, converging towards 
the lens, as seen in Fig. 82, correspond- 
ing in appearance with the ciliary bo- 
dies, and narrowed on the inner side ex- 
actly as the latter is. These appear- 
ances have been noticed by most writers, merely as the marks 





ZONA CILIARIS 403 

left by the ciliary processes ; but I have satisfied myself, by a 
careful microscopical examination of the eyes of different ani- 
mals, in the method advised by Mr. Jacob, confirmatory of the 
opinions of Knox, Camper, and Zinn, that it has a real existence, 
and consists of folds of the vitreous humour, which commence be- 
hind by a well defined margin and terminate in front, by being 
attached to the capsule of the lens ; the furrows between these 
folds being capable of receiving the folds of the ciliary bodies. 
By this means, these two bodies are firmly connected or dove- 
tailed together, one of which (the choroid) has considerable 
strength and firmness, and the other (the hyaloid tunic) is ex- 
tremely delicate in structure. By means of this connexion, the 
vitreous humour of the lens, through the medium of the ciliary 
ligament, becomes attached between the sclerotic coat and the 
iris, without which, the mechanical construction of the eye 
would have been imperfect. — * 

When the fluid contained in the tunica hyaloidea is discharged 
and collected, it appears to resemble, in all its properties, the 
fluid in the anterior chamber of the eye ; which, from its con- 
sistence, has been called the Aqueous Humour. This circum- 
stance proves that the particular consistence of the vitreous hu- 
mour is derived from the arrangement of its internal membranes. 

The fluid, thus obtained, consists of water slightly impregnated ; 
1st, with albumen, 2dly, with gelatine, and 3dly, with muriate of 
soda. 

The vitreous humour appears necessary, to give the ball of 
the eye the necessary size, for the performance of its optical 
functions ; to keep the retina properly distended, and to retain 
the crystalline lens at the proper focal distance from the retina. 

The Crystalline Lens 

Is a solid body ; although it is considered as one of the humours 
of the eye. It is of a softish consistence, and has been compared 
to gum half dissolved ; but is more firm in the centre than about 
the circumference. 

• Vide article Eye, in the Cyclopedia of Anatomy and Physiology, from which 
many of these figures have been taken. 




404 CRYSTALLINE LENS 

When sound it is perfectly transparent in young and middle- 
aged persons ; but is yellowish in old age. It is convex on both 
surfaces, but the convexity of the different surfaces is different. 
The anterior surface, which is the least convex, is the segment 
of a sphere, whose diameter varies from six to nine lines. The 
posterior surface, which is most convex, is the segment of a 
sphere, whose diameter varies from four lines and a half, to five 
lines and a half. This lens is most convex in young subjects. 

It is invested with a tunic of the same 

tig. w«i.* lenticular form with itself, which has 

some firmness ; but in a healthy state. 

is also perfectly transparent. The lens 

either does not adhere at all to the tunic. 

or so slightly, that it projects from it with a very slight pressure, 

as in the operation of extracting the cataract. 

The posterior surface of this tunic adheres firmly to the tunica 
hyaloidea, with which it is in contact : and this last membrane 
is generally ruptured in the atttempt to separate them, although 
the separation can sometimes be effected without rupture. 

The anterior surface is so intimately connected with that 
lamen of the hyaloid tunic which passes before it from the canal 
of Petit, that it is not separable without laceration ; and it, there- 
fore, has not been ascertained, whether or not this lamen extends 
completely over the surface. 

As the capsule of the lens is thus connected with the tunica 
hyaloidea, and this last mentioned tunic adheres to the ciliary 
body, it necessarily follows that the lens is confined in its proper 
position behind the pupil. 

Notwithstanding the soft consistence of the exterior portion of 

* Fig. 83 shows the difference of convexity in the lens at different periods of life, 
as represented by Sommering. To the left is the lens of a foetus. The middle one 
is that of a child six years of age; the right is that of an adult. The lens varies 
in consistence as well as colour, as life advances. In infancy it is soft and pulpv, 
in youth firmer, so as readily to be crushed between the thumb and finger — and in 
old age it becomes tough and firm. Hence the operation of cutting up the lens 
for the cure of cataract, is more appropriate in children than old persons, in whom, 
from its toughness, it is apt to roll under the needle and inflict injury on the 
iris. — p. 



CRYSTALLINE LENS. 405 

the lens, there is reason to believe that it has a peculiar organi- 
sation; for if it be immersed some time in a diluted solution of 
the nitrate or muriate of alumine, or in several other fluids, and 
then dried, it will be found to be composed of concentric lamellae, 
which resemble those of the bulbous roots; and these lamellse 
will appear to consist of fibres. 

It has been supposed that muscular fibres entered into the 
composition of the crystalline lens, but this opinion has never 
been generally adopted.* 

Between the lens and its capsule a small quantity of a trans- 
parent fluid is sometimes found, which escapes whenever the 
capsule is punctured. This fluid is supposed to be most abundant 
on the anterior surface, and is called liquor Morgagni. 

— The lens, according to Berzelius, consists of a peculiar coag- 
ulable albuminous matter, 35.9 — alcoholic extract with salts, 2.4 — 
watery extract with traces of salts, 1.3 — membrane forming the 
cells, 2.4 — water, 58.0. The liquid contained in its cells is more 
concentrated than any other in the body. The albuminous 
matter is peculiar, inasmuch as the concentrated solution in- 
stead of becoming a coherent mass on the application of heat, 
becomes granulated, exactly as the colouring matter of the blood 
when coagulated, from which it only varies in the absence of 
colour, and differs from fibrine in not coagulating spontaneously. 
— The lens, which at first sight appears to be a simple homoge- 
neous body, more consolidated, so as to form a sort of nucleus, 
at the centre, is in fact as elaborately organised as any part of 
the body. The concentric lamellae of which it is composed 
are resolvable into fibres. The arrangement of these fibres 
differs in the different classes of animals ; according to Sir D. 
Brewster, in birds and some fishes, as the cod and haddock, the 
fibres converge in straight lines, from the two opposite poles of 
the spheroidal lens, like the meridians of a globe. In some other 
fishes, in reptiles, and a few of the mammalia, the fibres do not start 
from a single point, but from two septae at each pole. The third 
or more complex structure exist in the mammalia in general, in 

* See Dr. Young's Memoir in the Philosophical Transactions for 1793. 



406 



STRUCTURE OF THE CRYSTALLINE LENS. 



Fig. 84. 



which three septce, as in Fig. 84, diverge from each pole of the lens, 
at angles of 120 degrees; the septa of the anterior surface bi- 
secting those of the posterior. The mode in which these fibres 
are laterally united, is very intimate-by a sort of recmrocahnden- 

tation or rack-work. 1 he 
lens in its embryotic de- 
velopement, is formed in 
three separate parts, which 
are subsequently united at 
the poles. If the lens is 
macerated for a short 
time in water, or water 
acidulated with mineral 
acid, it separates readily 
from the centre to the 
circumference in layers 
which may readily be re- 
duced to fibres, as seen in 
the human lens and 




in 



the lens of a fish, (Lophius piscatorius,) Fig. 85, taken from Pro- 
fessor Jacob. 



Fig. 85* 



— The opaque structure of the 
lens opens in this way in many 
cases of cataract and presents 
the stellated appearance seen 
through the transparent capsule. 
—The fluid called liquor Mor- 
gagni, said to exist between the 
capsule and lens, Professor 
Jacob considers a post mortem 
result, like that of the pericardium ; the fluid escaping from the 
cells of the lens. In the eyes of domestic animals examined 

* The small figure to the left in this cut, represents the human lens, macerated 
in water containing a few drops of acid for several days, when it is found split 
open by fissures extending from its centre to its circumference. The large figure 
to the right, is the lens of a fish prepared in the same way by Mr. Jacob ; its fibres 
unfolded with a delicate needle, and presenting a tufted appearance.— p. 




AQUEOUS HUMOUR. 407 

shortly after death no fluid is met with, but if many hours are al- 
lowed to elapse, a small quantity is found in the capsule. My 
own observations made both with the naked eye, and with the 
use of a strong lens, are in confirmation of his views. 
— This distinguished anatomist considers the semicartilaginous 
transparent capsule to be applied, immediately on the surface of 
the lens, and to preserve its pulpy exterior in the proper curva- 
ture. 

— Between the lens and capsule there is evident connexion at 
the back part, where Albinus has injected a vessel passing from 
the capsule to the lens. When the anterior part of the capsule 
is opened, Mr. J. believes it is the contraction or shrinking of the 
capsule which breaks the connexion, and forces the lens from 
its bed; an occurrence which we find does not always take place 
in operations upon the eye, without artificial aid. — 

No blood-vessels are to be seen in any of the humours of the 
eye, or their capsules, excepting those of the foetus. In the foetus 
a branch can be traced from the central artery of the retina, 
through the vitreous humour, to the posterior surface of the 
crystalline capsule, on which it ramifies. In similar subjects 
vessels have been seen passing from the ciliary processes to the 
anterior surface of the capsule ; and it is also asserted by very 
respectable anatomists that they have seen vessels passing from 
the capsule into the substance of the lens. 

The use of the crystalline lens is to concentrate the rays of 
light, so as to form a distinct image at the bottom of the eye. 

The Aqueous Humour 

Occupies the space which is between the crystalline lens and 
central extremities of the ciliary processes and the cornea. This 
space is divided by the iris into two chambers, very dissimilar 
in figure, which communicate with each other by means of the 
pupil. The posterior chamber is much smaller than the anterior, 
and its existence has been doubted ; but it is easily proved by 
freezing the eye, when it is found filled with a part of the aqueous 
humour in a state of congelation. 

The aqueous humour, in a natural state, is perfectly transpa- 
rent ; but in the foetus, and for a short time after birth, it is red- 



408 



CHAMBERS OF THE AQ.UEOUS HUMOUR. 



dish and turbid. It consists of water impregnated with albumen, 

gelatine, and muriate of soda ; and of course resembles the fluid 

of the vitreous humour. 

It is probable that this fluid has also a capsule appropriated to 

it ; for, after boiling an eye, a delicate membrane can be found 

lining the internal surface of the cornea, and extending from it 

over the anterior surface of the iris. It has not yet been traced 

as far as the pupil, but it is probable that it extends through the 

pupil, and lines the posterior chamber also.* 

The aqueous humour is quickly renewed after it has escaped 

in consequence of wounds or operations, and blood, accidentally 

effused into its cavity, is often absorbed.f 

This fluid preserves the convexity of the cornea, and admits 

the free motions of the iris ; allowing, at the same time, a ready 

passage to the rays of light. 

Fig. 86.J — The annexed enlarged cut from Som- 

mering, shows accurately the comparative 
size of the two chambers of the aqueous 
humour, and how the posterior is formed by 
the iris in front, the capsule of the lens be- 
hind, and the ciliary processes, and a small 
portion of the hyaloid tunic between these 
processes and the margin of the capsule, upon 
the side. 

— Petit has calculated, that the whole amount 
of the aqueous humour, does not weigh more 
than four or five grains, and that the space 

between the iris and the capsule of the lens is less than a 




* This capsule was discovered by Messrs. Demours and Dcscomet, who disputed 
each other's claim in 1767. It is thought to be useful in preventing the cornea 
from being penetrated by the aqueous humours, and the pigmentum nigrum from 
being washed off the iris, and making this humour turbid. M. J. Cloquet says, 
that he has traced it in the posterior chamber of the eye. From this account it 
appears that there is one capsule, in early foetal life, for the anterior chamber, and 
another for the posterior chamber, and that the Membrana Pupillaris is formed by 
these capsules being stretched across the pupil, back to back. — h. 

t The aqueous humour, according to Mr. Hunter, can be coagulated with Gou- 
lard's Extract. — h. 

| Memoirs of French Academy for 1721. 



DISSECTION OF THE EYE. 409 

quarter or half a line; while Winslow insisted, that the iris 
and capsule were in contact in youth and middle life, when the 
pupil was contracted. 

—Certain it is that adhesion takes place readily between them, 
and that the posterior chamber is so narrow, that no surgeon can 
with any certainty introduce an instrument into it, without the 
risk of wounding the vascular ciliary processes, or the iris. 
—The following are the dimensions and admeasurements made 
by Petit and Young, of the different parts of the globe of the eye. 

Inches. 

Length of the optical axis, . . . 0.91 

Vertical cord of the cornea, . . • 0.45 

Versed sine of the cornea, . . . 0.11 

Horizontal cord of the cornea, . . . 0.47 
Diameter of pupil as seen through ditto, 0.27 to 0.13 

Distance of iris from cornea, . . . 0.11 

Distance of iris- from anterior surface of lens . 0.02 

Radius of anterior surface of lens, . . 0.30 

Radius of posterior surface of lens, . . 0.22 

Principal focal distance of lens, . . 1.73 
Distance of the centre of the optic nerve from the 
central fold, {yellow spot, limbum luteum,) in the 
axis of vision, . . . .0.11 

Range of eye, or diameter of the field of vision, 1.100 

It will be very beneficial to every student of anatomy to dissect this deli- 
cate organ himself, as he will thereby acquire more accurate and precise 
ideas of its structure than he can possibly obtain from the ordinary demon- 
strations. 

The eyes of sheep and oxen will serve very well for beginners, as many 
of them will be required, and they can be easily obtained. They resemble 
the human eye in many respects ; and the circumstances in which they differ 
may be readily ascertained by the diligent student; especially if he dissects 
the human eye afterwards. 

For this purpose, it will be requisite to have forceps, finely pointed ; with 
knives and scissors that are equally delicate in structure ; and also a pair of 
strong scissors, bent like those in the cases of pocket instruments. 

When removing the exterior parts, it will be useful to preserve a portion 
of the optic nerve, to take hold of. 

vol. ii. 35 



410 DISSECTION OF THE EYE. 

The dissection of the coats of the eye can be best performed when the 
eye is placed in a vessel of water; which should be shallow or deep, accord- 
ing to the different stages of dissection. 

In some dissections it will be serviceable to form a bed of jelly, to support 
the eye, as proposed by Mr. C. Bell. 

As the first process in this operation, the sclerotic coat can be readily 
separated from the choroides, and the cornea with it. 

After examining the external surface of the choroides, the ciliary liga- 
ment, and the iris, the iris may be peeled off from the choroides. 

The choroides, by a careful process, may then be separated from the retina, 
which it leaves surrounding the vitreous humour. The ciliary processes, 
being a part of the choroides, come away with it. 

The preparation being in water may now be suspended by the optic nerve. 
It consists of the vitreous and crystalline humours and the retina. The 
retina, originating from the optic nerve, adheres anteriorly, also, with so 
much firmness, that it will support the part enclosed. 

The retina may be removed without lacerating the tunics of either of the 
humours ; and the pigmentum nigrum, which often adheres to that part of 
the vitreous humour which was connected with the ciliary processes, may 
be washed away with a piece of soft sponge. By this washing, the radiated 
grooves in the vitreous humour, which were connected with the ciliary 
processes, will be very apparent. 

To examine the iris in its natural situation, an aperture may be made in 
the cornea of a fresh eye near its circumference, and the cornea cut out with 
the strong scissors. This exposes the anterior surface of the iris. 

The iris may then be easily removed, and the crystalline lens, with the 
central extremities of the ciliary processes surrounding it, will be exposed 
to view. 

To examine the ciliary processes on the other side, a lancet may be 
plunged into another eye, somewhat anterior to the middle, and the eye 
divided by means of the strong scissors. The anterior section should then 
be laid on the cornea, and the ciliary process will appear very distinctly, 
seen through a portion of the vitreous humour. The retina may also be 
seen at the same time, and a judgment may be formed of its extent. The 
view will be more distinct, if part of the vitreous humour should be cut away 
with the scissors and forceps, so as to lessen the quantity without deranging 
the parts under it. 

Several methods have been proposed for rendering the structure of the 
vitreous humour, and the processes of the tunica hyaloidea, more distinct. 
None of them have been very successful: but, if the vitreous humour be 
suspended in water by means of a thread passed through that part which 
surrounds the crystalline lens, and some large incisions be made into the 
most depending part of it, after some days of suspension its bulk will be 



DISSECTION OF THE EYE. 4JJ 

diminished, by the discharge of the fluid. If, in this situation, it be immersed 
in a solution of nitrate of silver, the tunica hyaloidea will become very ap- 
parent ; and, by various degrees of exposure to light, may have its colour 
varied from a whitish opacity to a dark brown. 

The appearance of the retina is also much changed by immersion in the 
solution of nitrate of silver. This effect of the solution, at first sight, ap- 
peared calculated to decide the question respecting the extent of the retina; 
but, after several applications, it could only be said, that the pulpy substance 
of the retina appeared to terminate at the commencement of the ciliary 
processes, while a membrane of a different texture seemed continued from 
it to the crystalline lens. 



412 THE EAR. 



CHAPTER XV. 

OF THE EAR. 

Thk organ of hearing is composed of three distinct parts, viz. 
1. The exterior portion, which, although merely auxiliary, is 
denominated the External Ear. 2. A chamber, situated in the 
petrous portion of the temporal bone, which is called the Cavity 
of the Tympanum. 3. A deeper seated cavity in the same bone, 
which, from its complicated form, is denominated the Labyrinth. 

Of the External Ear. 

The External Ear consists of the expanded portion, exterior to 
the head, commonly called the Ear, and a wide tube passing 
from it to the cavity of the tympanum, called Meatus Auditorius 
Externus. 

The form of the Ear is so familiar to every one, that it is not 
necessary to describe it. The uppermost and longest portion is 
denominated Pinna. The small pendulous part below is called 
Lohus. 

The form as well as the firmness of the pinna, depends en- 
tirely upon a cartilage: the lobus consists of skin and cellular 
membrane. 

The skin which covers the pinna is particularly delicate; and, 
when the cuticle is separated from it by maceration, it appears 
to be perforated with an unusual number of foramina, which are 
the orifices of the sebaceous glands. It is connected to the sub- 
jacent cartilage by a dense cellular membrane, which, in most 
places, is free from adeps. 

The cellular membrane of the lobus contains adeps very deli- 
cately arranged. 

The circumference of the ear is formed by a fold of the mar- 
gin of the cartilage : and this folded edge is denominated Helix, 



OF THE EXTERNAL EAR. 413 

from its winding direction. It commences in the cavity called 
Concha, to be presently described; and, after proceeding for- 
wards and upwards, it turns round backwards and downwards. 

Within this prominent margin is a second prominence, called 
the Antihelix, which appears to be formed by a convexity of the 
surface of the cartilage, but is found in every ear. It is nearly 
semicircular, with its concavity towards the meatus; and it 
forms the margin of the cavity called Concha, above mentioned. 
The upper portion of the antihelix consists of two superficial 
ridges, which unite after forming between them a shallow 
depression, the Fossa JVavicularis, or Scapha. 

The helix and antihelix form, therefore, three cavities or de- 
pressions, viz. 1. A sulcus, occasioned by the fold of the helix, 
which is sometimes called Fossa innominata. 2. The Fossa JVa- 
vicularis ; and 3. The Concha, which may be considered as the 
proper orifice of the ear. 

Besides these prominences and fossae there are two other emi- 
nences, called Tragus and Antilragus, formed, also, by this car- 
tilage. The Tragus is anterior to the meatus auditorius, and 
covered by a continuation of the skin of the face. It projects 
backwards, so as partly to cover the meatus. On the inside of 
it there is commonly a tuft of hair, from which its name is 
derived. 

The Antitragus is opposite to the tragus, on the posterior 
margin of the concha. 

On the posterior surface of the ear the convexity of the 
concha is very conspicuous. 

When the skin and cellular membrane is carefully removed, 
and the cartilaginous skeleton of this structure is examined, its 
form will not appear so regular as that of the undissected ear; 
for there are several deficiencies or vacuities in it; the most 
remarkable of which is between the tragus and the helix. 

The cartilage thus formed is attached to the bones of the face 
and cranium, by three ligamentous membranes, which connect 
it to the zygomatic and the mastoid processes of the temporal 
bone, and to the aponeurosis on the squamous portion of the same 
bone. 

35* 



414 0F THE EXTERNAL EAR. 

In addition to the common muscles of the ear, described at p. 
274, vol. i. there are a few muscular fibres, which, in some sub- 
jects, may be discerned on particular parts of the cartilage, and 
therefore are considered as muscles proper to these portions of 
the ear. 

There are five of these portions of fibres ; two on the helix, 
one on the tragus, one near the antitragus, and the fifth on the 
other side of the ear. 

The Major Helicis is on the anterior and most prominent part 
of the helix above the tragus. The Minor Helicis is lower down 
on the helix in the concha. 

The Tragicus lies on the tragus, and the Antitragicus behind 
the antitragus, while the Transversus Auris is on the other side 
of the ear, on the prominence formed by the concha near its 
circumference. 

It may be observed respecting the muscles of the ear, that 
even the common muscles, which are by far the largest, are un- 
able, in many persons, to move that organ ; and the proper mus- 
cles, in a large majority of mankind, cannot be perceived to 
produce any effect at all. 

There are difficulties in explaining the form of the cartilage; 
for, notwithstanding the well known opinion of the geometrician 
said to have been employed by Boerhaave, that the line of rever- 
beration is directed to the meatus auditorius externus from every 
part of the ear, in many persons the cartilage is so situated that 
the concha appears to be the principal, if not the only part, from 
which sound can be reverberated into the meatus. 
• It may be questioned whether the backward position of the 
ear, which is commonly observed at the present day, is alto- 
gether natural ; as a more prominent position seems much better 
calculated for the reverberation of sound; but this position of the 
cartilage is observable in many infants at birth. 

It is asserted by some comparative anatomists, that the carti- 
lage is stronger and more elastic in proportion to its size, in man, 
than in any other animal; and that the lobus is peculiar to the 
human ear. 

The Meatus Auditorius Externus is a tube, extending from the 



MEATUS AUDITORIUS EXTERNUS. 41 5 

concha to the membrana tympani, the external extremity of 
which is principally composed of cartilage, and the internal of 
bone. The cartilage in the external portion of the tube is a con- 
tinuation of the substance of the concha. It does not solely form 
a complete tube, for, when the meatus is opened longitudinally 
and spread out, this cartilage appears triangular in shape; a 
fibrous membrane being joined to it to complete the tube. 

In addition to the deficiency thus arising, there are two others* 
one of which, that has a transverse position, is of considerable 
size. These deficiencies are called Incisures; and the fibrous 
structure which closes that which is transverse, has been called 
by Santorini, who described it, Musculus Incisurcn Majoris. 

The cartilage is attached to the bony portion of the meatus at 
the lower part of its margin, and forms about one half of the 
length of the meatus. 

The skin covering the external ear is continued into the 
meatus, and lines it throughout ; extending over the incisuroe, 
and also over the membrana tympani. It adheres more firmly 
to the periosteum of the bony part of the meatus than to any 
other portion of the canal. Some fine hair is often observable 
growing out of it at the external extremity. As the skin ad- 
vances deeper in the meatus it becomes more and more delicate 
and sensible. The extreme pain excited by the penetration of an 
insect, or the introduction of an instrument, into the ear, evinces 
the great degree of sensibility with which it is induced. 

Exterior to the skin, in the cellular membrane which sur- 
rounds it, are many small glands* of a yellowish colour, whose 
ducts open upon the surface of the meatus, and pour upon it the 
substance called cerumen or ear-wax. These glands are most 
numerous about the middle of the meatus and at those places in 
which the cartilage is deficient. The cerumen is fluid at first, 
and gradually thickens. In some diseases of the meatus it has 
the appearance of pus. The use of this secretion is probably to 
exclude insects, for which it is well calculated by its tenacity 

• Discovered by Stenon, in 1662. — h. 



416 CAVITY OF THE TYMPANUM. 

and bitterness; and also to defend the delicate surface upon 
which it is spread. 

The direction of the meatus is inwards and forwards: it is 
also curved, with the convexity upwards ; but it is very easy, 
by management of the external ear, to admit the rays of the sun 
to the bottom of the meatus, and bring the membrana tympani 
into view. 

— Its length, in the adult, is about ten or twelve lines. It is a 
little greater along the inferior part of the meatus, in consequence 
of the oblique manner in which it is closed at its internal extre- 
mity, by the membrana tympani. See Plate xiii. 
— The cerumen is composed, according to Vauquelin, of a fatty 
oil, of a peculiar albuminous substance, and yellow colouring 
matter. According to Rudolphi and Fourcroy, the bitter prin- 
ciple of the cerumen is the same as that of the bile. 
— The external ear is a simple acoustic instrument, a sort of 
trumpet, for the purpose of catching the sonorous vibrations, and 
transmitting them to the membrane of the tympanum, to which 
it is connected by the meatus auditorius externus. Its re- 
moval, however, does not appear to impede, very seriously, the 
function of hearing, as the rays still find their way down the 
meatus. It is not found in purely aquatic animals, but in those 
only which hear through the medium of the air. In some birds, 
and some reptiles, there are, in front of the tympanum, two sorts 
of lips, susceptible of opening and shutting, like the eyelids. — 

A vertical section of the meatus is of the oval figure. In the 
foetus the bony part of this duct is not formed, and the meatus 
consists entirely of cartilage. 

Of the Cavity of the Tympanum. 

The meatus auditorius externus is terminated abruptly by the 
membrana tympani, which forms a septum that closes it com- 
pletely. 

On the inner side of this septum is the Cavity of the Tympa- 
num, which may be regarded as the continuation of the bony 
meatus. 



CAVITY OF THE TYMPANUM. 417 

It differs, however, from the form of this canal ; for its diame- 
ter is greater, and it is not so regularly cylindrical. 

It is not deep; as the distance from the membrana tympani, 
which constitutes the external side, to the opposite internal side, 
is seldom more than three or four lines. 

— Its antero-posterior diameter is about six lines, and its vertical 
diameter rather more : though from the inequality of Us surface, 
and its connexion with the mastoid cells and Eustachian tube, 
it is difficult to assign its exact dimensions. — 

The breadth of the cavity of the tympanum is, therefore, 
greater than its depth. 

It is situated immediately between the membrana tympani, 
and the labyrinth which is on the inside of it. 

In its natural state this cavity has two apertures ; one which 
communicates with the fauces, by means of the Eustachian 
Tube; and another which leads into the cellular structure of the 
mastoid process. 

There are also two deficiencies in the bony plate, which se- 
parates it from the labyrinth, called the Foramen Ovale, and Fo- 
ramen Rotundum; but in the natural state of the parts these de- 
ficiencies are closed, and there is no direct communication of the 
tympanum either with the labyrinth or the meatus auditorius ex- 
ternus: the only direct communications being those above men- 
tioned, with the fauces and the mastoid cells. 

That deficiency in the bone between the tympanum, and the 
labyrinth, which is called Foramen Ovale, is closed by one of the 
small bones of the car, called the Stapes. The other deficiency, 
called Foramen Rotundum, is covered by the membrane which 
lines the tympanum. 

In the cavity of the tympanum are four of the smallest bones 
of the body, which are articulated with each other so as to form 
one flexible piece. This piece is attached by one end to the 
membrana tympani, and the other to the Foramen Ovale; and it 
is moved by small muscles connected with it. 

The cavity of the tympanum is lined by a membrane which 
has been considered as similar to the periosteum : but it is as- 



418 CAVITY OF THE TYMPANUM. 

serted by Bichat that this membrane, when inflamed, resembles 
the mucous membranes ; and that in its natural state it secretes 
a mucus which passes into the fauces by the Eustachian tube. 

This lining membrane is continued over the internal surface 
of the membrana tympani, and was supposed by the aforesaid 
author to be reflected so as to cover the small bones of the ear. 

The opinion of Bichat, respecting the nature of the membrane, 
is rendered probably by analogical reasoning, viz. The internal 
surface of the cavity must be in want of mucus or cuticle, as it 
is in contact with the air. The membrane is very sensible in a 
sound state, and therefore is very different from periosteum, 
which it was supposed to resemble. 

— The tympanum or middle ear, is but an accessory part of 
the organ of hearing, the use of which is to augment and trans- 
mit sound received through the medium of the air. It is found 
only in mammalia, birds, and reptiles. The whole organ of 
hearing in fishes, consists merely in a membranous bulb, placed 
at the exterior, and upon which is ramified the auditory nerve. 
— The most simple idea that can be formed of the tympanum, 
(as seen in its developement in the human foetus and in inferior 
animals,) is, that of a cylindrical prolongation of the mucous 
membrane of the pharynx, to the front part of the labyrinth. 
There it is dilated to form the cavity of the drum, and contracted 
on the side of the pharynx to form the Eustachian tube. A bony 
shell is subsequently formed around the drum, and the tympanic 
half of the Eustachian tube. The closure of the tympanum by 
bone, is not complete. The membrana tympani forms part of 
the wall on the side of the meatus. The internal wall of the 
cavity of the tympanum, is formed by the bony labyrinth. The 
mucous membrane reflected from the pharynx into the cavity of 
the tympanum, is extremely thin and delicate, is very vascular 
and receives many filaments of nerves. It lines the whole 
circumference of the cavity, as well as the mastoid cells com- 
municating with it, and is reflected over the chain of bones, and 
subserves the part of capsular ligament in holding them together 
at their articulation.-— 



MEMBRANA TYMPANI. 4jg 

The Membrana Tympani, 

Appears to be fixed, in a bony ring in the meatus auditorius, 
and is nearly circular in form. It is not perpendicular to the 
meatus, but has an oblique position in it; the inferior margin 
projecting farther inwards than the superior. 

The external surface forms a conical concavity, being ap- 
parently drawn in by the malleus, one of the small bones of the 
ear, to which it is attached.* 

It is asserted by several anatomists, that this membrane may 
be separated into four lamina, viz. 1. The Cuticle; and, 2. The 
Cutis; which are continued from the skin of the meatus ex- 
ternus. 3. The proper Membrana Tympani ; and 4. The Lining 
Membrane of the Tympanum; which is extended over the internal 
surface of the membrana tympani. Notwithstanding these la- 
mina?, it is almost transparent in the living subject, when in a 
healthy state, and appears highly polished on its external surface, 
when light is thrown upon it. It has been injected so as to 
appear vascular in every part; and one or two vessels are some- 
times seen even in common injected preparations. In some 
cases of inflammation it has been uniformly red. 

It was formerly asserted by Rivinus, a professor at Leipsic, 
that there was a natural aperture in this membrane; but although 
this opinion has had several votaries, it is certainly erroneous. 
At the same time it is to be observed, that an aperture, occa- 
sioned by accident or disease, is sometimes perceived in persons 
who enjoy the faculty of hearing to a considerable degree. 
Some persons, thus circumstanced, are accustomed to force 
tobacco smoke from the mouth through the ears. 

It is asserted by a respectable anatomistf that the membrana 
tympani, when viewed in a microscope, which will magnify 
twenty-three times, appears to be supplied with muscular fibres 

* In birds, it is always found convex outwards. This is a universal mark of 
distinction in the membrana tympani of birds and mammalia, the two classes of 
animals only, in which it exists as a thin vibrating 1 membrane. — p. 

t Sec Mr. Home's Memoir on the structure and uses of the membrana tympani, 
in the Philosophical Transactions for 1800. 



420 



EUSTACHIAN TUBE. 



arranged in a radiated manner. These fibres are on the internal 
side of the membrane. He thinks that, under favourable cir- 
cumstances, they can be seen with the naked eye. 

Fig. 87.* 



o^, 




h 9 /?" e'"-f e 6 



The Eustachian Tube. 

The communication between the cavity of the tympanum and 
the fauces is formed by the Eustachian Tube, a canal which con- 

* Fig. 87 represents a vertical section of the auditory apparatus of the left side • 
the labyrinth being a little enlarged, in order to render its description more intelli- 
gible to the student, a, External ear. b, Lobus of the ear. c, Antitragus. 

d, Concha, the bottom of which is continuous with the meatus auditorius externus. 

e, e, Petrous portion of the temporal bone, in which the auditory apparatus is 
lodged, e', Mastoid process of the temporal bone, c", Portion of the glenoid 
cavity of the temporal bone, in which is articulated the condyle of the lower max- 
illary bone, c'", Styloid process of the same bone, c"", Extremity of the carotid 
canal, traversed by the internal carotid artery, before it penetrates into the cavity 
of the cranium. /, Meatus auditorius externus. g, Membrana tympani. A, Ca- 
vity of the tympanum, from which the chain of bones have been removed, i, Two 
openings leading into the cells of the petrous portion of the temporal bone. On the 



EUSTACHIAN TUBE. 421 

sists of bone at one extremity, and of cartilage at the other. It 
commences in the upper and anterior part of the cavity of the 
tympanum, and continues forwards and inwards through a part of 
the petrous portion of the temporal bone, above the fissure in the 
cavity for receiving the condyle of the lower jaw. The bony 
canal terminates in a very rough and irregular orifice, which is 
united to a tube composed of cartilage and of membrane, that 
terminates by a large orifice behind the inferior turbinated bone 
of the nose, and on a line with it. 

—The whole length of the Eustachian Tube is nearly two 
inches. The bony portion is about eight lines long; the cartila- 
ginous from an inch to an inch and a quarter. The latter rests 
against the side of the internal pterygoid process of the sphenoid 
bone, to the periosteum of which it is attached ; and on its under 
surface gives attachment to some of the muscles of the palate. 
The course of the tube is nearly horizontal, as it runs outwards, 
backwards, and slightly upwards. The opening of the tube into 
the fauces is funnel-shaped and large enough to receive the end 
of the little finger. It "contracts suddenly, at the place of union 
of the cartilaginous and bony portion, and it is there barely large 
enough to admit a good sized bristle. From this point the cali- 
bre of the tube again increases somewhat in size, in its course to 
the cavity of the tympanum. — 

This tube is lined by a continuation of the membrane of the 
posterior nares, which becomes more thin as it proceeds towards 
the cavity of the tympanum. 

Above the Eustachian Tube, and separated from it by a thin 
plate of bone, is a small canal which is nearly parallel to it, and 
continues so to the end of the petrous bone ; this contains the 
internal muscle of the malleus. 

internal wall of the cavity of the tympanum, are seen two openings, the fenestra 
ovalis, leading to the Vestibule, I; and the fenestra rotunda, leading to the cochlea, 
n. m, Semicircular canals, k, Eustachian tube leading from the pharynx to the 
cavity of the tympanum, o, Auditory nerve. The protuberance made on the in- 
ternal wall of the cavity of the tympanum, is called the promontory. The opening 
called apertura chorda, and the pyramid, are on the posterior wall of the tympanic 
cavity, and cannot be well seen in this figure. 
vol. ii. 36 



422 FORAMINA AND PROTUBERANCES OF THE TYMPANUM. 

The Mastoid Cells. 

In the upper and back part of the cavity of the tympanum, 
nearly opposite to the orifice of the Eustachian Tube, is an open- 
ing which communicates with the cells of the mastoid process. 
These cells do not appear different from those in other bones, 
and are lined with a membrane apparently similar. Their size 
is proportioned to that of the mastoid process, and consequently 
they do not exist in the foetus. 

— The mastoid cells or sinuses, communicate freely with one 
another, and with the cavity of the tympanum, at the posterior 
superior part of the latter. The opening into the cavity of the 
tympanum is irregular and lodges the short leg of the incus. 
The mastoid cells, are analogous in structure to the frontal and 
sphenoidal sinuses; they differ entirely from the common cellu- 
lar tissue or diploic structure of bones. The latter is placed be- 
tween the two tables of the bones, whilst the sinuses have both 
tables on their exterior, forming their varieties with the usual 
diploic structure between them. — 

Foramina and Protuberances of the Tympanum. 

That part of the surface of the cavity of the tympanum which 
is opposite to the membrana tympani, is very irregular, but it 
contributes to the formation of several parts which are very 
important in the structure of the ear. 

When the lining membrane is removed, the aperture called 
Foramen Ovale {fenestra ovalis), appears in a conspicuous situa- 
tion, rather above the middle of this surface. It would open di- 
rectly into the Vestibule, or middle chamber of the Labyrinth; 
but it is closed by the base of the stapes. 

Above the foramen ovale is a prominence of the surface, in 
which passes the canal for the Portio Dura of the seventh pair of 
nerves. 

Under the above mentioned foramen is a more striking protu- 
berance called the Promontory, within which is a part of the 
Cochlea, the anterior division of the Labyrinth. 

At the under and posterior part of the promontory is the Fo- 



BONES OF THE EAR.-MALLEUS-INCUS. 423 

ramen Rotundum (fenestrarotunda), which opens into the Cochlea. 
This foramen is smaller than the foramen ovale ; and in its recent 
state is covered by the membrane which lines the tympanum. 

— According to M. Ribes,* the membrane closing the fenestra 
rotunda, is a secondary membrane of the tympanum, formed of 
three layers; viz. the lining membraneof the tympanum, the lining 
membrane of the cochlea, and between them a peculiar middle 
membrane like that which closes the bottom of the meatus audi- 
torius externus. 

— It is probable that a similar arrangement, exist at the fenestra 
ovalis, and upon which the stapes rests, though it has not been 
satisfactorily demonstrated. 

— The size of both these fenestras, is greatly inferior to that of 
the membrana tympani. — 

Behind the foramen ovale is a protuberance with a perforation 
in it. This is called the Pyramid. Tt is excavated, and contains 
the muscle of the stapes, which passes out through the perforation. 

The Bones of the Ear. 

The four small bones in the cavity of the tympanum are 
denominated Malleus, Incus, Orbiculare, and Stapes. (See Fig. 
88, p. 426.) 

The Malleus resembles a crooked club more than any of the 
hammers now in use. It consists of an irregular roundish head, 
a neck, and a long tapering body, called the Manubrium, or 
handle. It has also two processes ; one arising from the neck, 
which is long and slender, like a bony fibre, and, therefore, called 
Gracilis. The other, called Brevis, arises from the upper end 
of the handle. The handle of the Malleus forms an angle with 
its body, the salient side of the angle presenting outwards: the 
space from this angle to the termination of the manubrium, or in 
other words the whole manubrium is connected with the mem- 
brana tympani. 

The Incus resembles a molar tooth, with two roots, widely se- 
parated from each other. On the body is a depression which 
is connected with the head of the malleus. One of the roots or 
crura is much longer than the other. 

* Memoire sur Quelques Parties de l'Oreille Interne. 



424 BONES OF THE EAR.— ORBICULARE— STAPES. 

The Os Orbiculare is equal in size to a small grain of sand. 
It is connected to the extremity of the long cms of the incus, 
and to the upper part of the stapes. 

The Stapes has a strong resemblance to the common stirrup. 
The upper part is called its head, the lower part its base, and 
the two lateral portions its crura. One of the crura is longer 
than the other. A groove is also observed on the inner side of 
its crura, when they are examined with a microscope. The 
base is applied to the Foramen Ovale. 

The situation of these bones is such that the head of the mal- 
leus and the body of the incus are in the upper and anterior part 
of the cavity of the tympanum, which extends above the mem- 
brana tympani. The malleus is the most anterior of the two 
bones: its manubrium projects downwards, and is included be- 
tween the internal lamen of the membrana tympani and the 
membrane itself. Its long process extends horizontally, inwards 
and forwards, into the fissure of the glenoid cavity. 

The incus is so placed that the depression on its body receives 
the head of the malleus. The shortest leg projects backwards 
horizontally, and is attached by a ligament to a point in the 
opening into the mastoid cells. While the long leg projects 
downwards like the handle of the malleus, but behind it, and at 
a small distance inwards from the membrana tympani. 

The situation of the stapes is almost at right angles with the 
long leg of the incus, projecting inwards. Between the head of 
the stapes and the long leg of the incus, the os orbiculare inter- 
venes. 

When these bones are viewed in their natural position, the 
short leg of the incus projects horizontally backwards, the long 
process of the malleus horizontally forwards; the handle of the 
malleus, and the long leg of the incus, directly downwards, one 
connected with the membrana tympani, and the other with the 
foramen ovale, by the intervention of the orbiculare and stapes.* 

* Lassus, in his excellent discourse on Anatomy, informs us that Fallopius and 
Eustachius described nearly the whole interior of the ear. The most ancient au- 
thors had remarked the thin and transparent membrane which closes the extremity 
of the meatus externus. Fallopius described particularly the tympanum ; of the 



MUSCLES OF THE BONES OF THE EAR. 425 

The Muscles of the Bones of the Ear. 

The aforesaid bones appear to be regularly articulated for 
motion with each other, and they are furnished with several 
muscles. 

One of these muscles runs in the bony canal above the Eus- 
tachian tube, and is inserted into the posterior side of the handle 
of the malleus, below the root of the long process. Its effect is 
to draw in the malleus and membrana tympani. It is therefore 
called Tensor Tympani, or Internus Auris. 

Another muscle, as it is supposed to be, runs in the fissure on 
the outside of the Eustachian tube, and is inserted into the long 
process of the malleus. 

This is supposed to draw the malleus obliquely forward, and 
of course to relax the tympanum. It is therefore called Laxator 
Tympani, or Externus Mallei ; but there are the strongest doubts 
respecting the muscularity of this organ. 

Morgagni, Haller, Lieutaud, and Meckel, could not satisfy 
themselves that it was muscular; and Sabatier also doubts it; 
while Bell, Fyfe, Hume, Bichat and Gavard, appear to adopt 
the opinion of its muscularity. 

Some anatomists describe a third muscle of the malleus as 
arising from the superior posterior margin of the meatus audito- 
rius, where the membrana tympani adheres to if, and uniting to 
the neck of the malleus. It is supposed to draw the malleus and 
membrana tympani upwards and forwards. This, however, is 
noticed by few authors. (It is called the Laxator Tympani 
minor.) 

The stapes is also supplied with one muscle called the Stape- 
dius, which lies in the cavity of the pyramid. Its tendon passes 
through the foramen in that protuberance, and is inserted into 

four bones within it, the malleus, incus, os orbiculare, and stapes; Berenger de 
Carpi described the two first; Ingrasias, Eustachius, Columbus, and Louis Col- 
lada, a Spanish physician, disputed the discovery of the fourth with each other; 
and Vesting assures us that Francis de la Boe, a Dutch physician, discovered the 
third, which is the smallest. — h. 

36* 



426 



CHORDA TYMPANI. 



Fig. 88.* 
9 



the posterior part of the head of the stapes. It pulls the head of 
the stapes upwards and backwards. 

— Breschet, in a recent ad- 
mirable paper on the organ of 
hearing, after very careful re- 
searches on the subject, ad- 
mits but two muscles to the 
chain of bones, the tensor tym- 
pani or internus auris, and the 
stapedius, which he calls laxa- 
tor tympani. In birds, there 
is but one muscle attached to " ,' #/ ^ipP\ ^ ^H£---f 

the chain of bones, and that is /* \ \ \ 

a tensor of the tympanum. In / .' \ \ 

reptiles, when the chain of & ~b c b 

bones was met with, Breschet was unable to discover any mus- 
cle. — 




The Chorda Tympani. 

In the upper and posterior part of the cavity of the tympanum 
is a small nervous chord which enters by a foramen near the 
basis of the pyramid, and passing downwards and forwards, 
goes out at an aperture in the fissure of the cavity for the head 
of the lower jaw. In this course it crosses the long leg of the 
incus, and the manubrium of the malleus, and passes between 
them, being in contact with the manubrium. 

This nerve comes off from the portio dura immediately be- 



Fig. 88, is a magnified representation of the cavity of the tympanum, and its 
chain of bones, a, a, Cavity of the tympanum, b, Membrani tympani. c, Ma- 
nubrium of the malleus, the end of which is attached to the middle of the mem- 
brani tympani. d, Head of the malleus articulated with the incus, e, Processus 
gracilis, arising below the neck of the malleus, and extended into the glenoidal 
fissure of the temporal bone; upon its extremity is inserted the laxator tympani 
muscle of the malleus, if it really exist. /, Tensor tympani muscle, g, Incus, 
the horizontal short leg of which is placed in the cavity leading to the mastoid 
cells, the long vertical leg of which is articulated with the os orbiculare, h. 
i, Stapes, the top of which is articulated with the os orbiculare, and the base rests 
upon the membrane, closing the fenestra ovalis. fc, Stapedius muscle. — p. 



CHORDA TYMPANI. 427 

fore it emerges from the foramen stylo-mastoideum, and after 
passing a short distance through a small canal, enters the cavity 
of the tympanum as above described. After passing out of the 
cavity of the tympanum, it joins the lingual branch of the fifth 
pair of nerves. 

It was believed by the late Mr. John Hunter, that the chorda 
tympani is not simply a branch of the portio dura, but that it is 
the twig of the reflected branch of the spheno-palatine nerve, 
which, entering the os petrosum by the Vidian Foramen, joins 
the portio dura; and after passing with it a considerable dis- 
tance, leaves it at the place above described.* 

There is the greatest reason to believe that the principal object of the struc- 
ture above described, is to transmit to the labyrinth those impulses of the 
air which occasion sound. The membrana tympani, with the small bones 
and their muscular appendages, seem to be the agents for this purpose. 
The Eustachian tube and the mastoid cells are subservient parts. The 
effect of the chorda tympani in the cavity has not been ascertained. 

With this view of the subject, it is surprising that persons, in whom the 
membrana tympani has been destroyed, should enjoy the sense of hearing 
in a very considerable degree of perfection. Such, however, is the fact. 

It is necessary that there should be a communication between the cavity 
of the tympanum and the external air, in order that the function may be 
duly performed. 

This is evinced by the deafness which results from the obstruction of the 
Eustachian tube, and the cure of this deafness by relieving that obstruc- 
tion; as well as by the salutary effects of opening the membrana tym- 
pani;! and even of instituting a communication through the mastoid cells, 
in cases where the obstruction of the Eustachian could not be removed. 

It has been supposed that the Eustachian tube has the effect of transmitting 
sound to the ear, and particularly the voice of the individual of whose 
structure it is a part; and it is certain that we hear our voices very dis- 
tinctly, (although peculiarly modified,) when the external orifice of the 
ears are closed : but the well-known fact, that a small watch, when placed 
in the mouth, and not in contact with any part of it, is scarcely heard, if 

* I have followed Mr. H. in this dissection, and have no doubt of his opinion 
being correct. — h. 

T See Dr. Sim's paper on this subject, in the first volume of Memoirs of the 
Medical Society of London ; and Aslley Cooper's, in the London Philosophical 
Transactions. 



428 THE BONY LABYRINTH. 

heard at all, renders this opinion very doubtful. It ought, however, to be 
remembered, during the investigation of this subject, that persons who 
hear with difficulty are almost invariably in the habit of opening their 
mouths when they listen. 

Of the Labyrinth. 

Those parts of the organ of hearing which have been already 
described, seem calculated for concentrating the vibrations of air ; 
and for communicating, with some modification, the motion they 
occasion, to the Labyrinth. 

This important portion of the ear consists of three very dis- 
similar -parts, which communicate with each other, and form one 
general cavity. 

The central part of the cavity is a chamber, of a form which 
approaches to the oval, and has been compared to that of a grain 
of barley. It is called the Vestibule. 

At one extremity of this chamber (the posterior) are three 
tubes, each of which is curved so as to form a large portion of 
a circle. These tubes communicate with the vestibule, by each 
extremity; but they form only five orifices, because two of their 
extremities are united before they open into the vestibule. These 
tubes are denominated the Semicircular Canals. 

At the other extremity of the vestibule is a conical tube con- 
voluted like the shell of a snail. This is called the Cochlea. It 
also communicates with the vestibule. 

The Labijrinth, thus complicated in its form, is situated on the 
inner side of the cavity of the tympanum. Its position in such, 
that the Vestibule, and the Cochlea are opposite to the Membrana 
Tympani, and the Semicircular Canals are posterior to it. The 
apex of the cochlea is on the side of the labyrinth which is next 
to the tympanum, the basis of the cochlea is next to the brain. 

The texture of the bone which immediately surrounds these 
cavities is much harder than that of the other parts of the os 
petrosum ; and if the bone of a foetus be used, these softer parts 
may be cut away so as to leave behind the bony substance 
which surrounds these cavities, corresponding exactly to their 
form. 



VESTIBULE.-COCHLEA. 429 

The Labyrinth, when thus prepared, may be considered as a 
solid body which has been enveloped in a softer substance, and 
is brought into view by detaching the soft substance, which sur- 
rounded it. 

In the fofitus it is nearly as large as in the adult, so that the 
structure of the ear can be investigated with great advantage in 
such subjects. 

The Vestibule 

Is situated within the Foramen Ovale. There are two remark- 
able depressions of its internal surface; one, which is in the 
superior part, is called Semi-elliptical; the other, which is below, 
has the name of Hemispherical. 

When the dried preparation is examined, there are several 
foramina in this cavity, viz. the Foramen Ovale, already men- 
tioned. A round aperture, by which it communicates with one 
of the cavities of the cochlea, and the five openings of the semi- 
circular canals. Besides these, there are several small perfora- 
tions from the Meatus Auditorius Internus for the transmission of 
nerves. 

The Cochlea 

Commences at the anterior part of the vestibule. It is a coni- 
cal tube, so convoluted that it has the form of the shell of a snail 
making two circuits and a half round a centre. 

It may be considered as wound in a spiral direction round a 
pillar of bone. To this central pillar the name of Modiolus is 
applied. It commences at the cavity called Meatus Auditorius 
Internus; and its base is somewhat excavated. It gradually di- 
minishes in diameter as it proceeds towards the apex of the 
cochlea, and is, therefore, conical in form ; but it does not pre- 
serve this form to its termination, for near the apex it gradually 
becomes broader, and thus forms a second cone inverted. This 
last portion of the central pillar is called the Infundibulum. It 
is hollow ; and the portion of bone which covers its cavity, con- 
stitutes the basis of the inverted cone and the apex of the coch- 
lea. It is called the Cupola. 



430 LAMINA SPIRALIS AND SCALA OF THE COCHLEA. 

The tube thus wound round the modiolus, or the cochlea, is 
divided from the beginning to the end by a partition. 

The cavities are called Scalce, and the partition Lamina Spi- 
ralis. 

The Lamina Spiralis is made up of four parallel strips, which 
compose its breadth. 

1st. A plate of bone. 

2d. Outside of this, a softer plate, which appears cartilaginous. 

3d. A cellular portion, which appears to contain a pellucid 
fluid. 

4th. A thin membranous strip, which completes the septum or 
partition. 

These parts maybe distinguished from each other, when mag- 
nifying glasses of sufficient power are used. 

The bony plate is composed of two lamina with small can- 
celli between them, in which are canals for the transmission of 
the fibres of nerves. These canals are extended into the carti- 
laginous part. 

The membranous part which completes the septum is con- 
tinued into the lining membrane on the surface of the cochlea. 

The bony portion of the scala does not extend towards the 
apex of the cochlea so far as the cartilaginous and membranous 
portions ; and none of them continue to the apex, for the lamina 
spiralis terminates in the infundibulum before it had arrived at 
the apex. Its extremity has the form of a hook, and is, there- 
fore, termed Hamulus. 

As this septum does not extend to the apex of the cochlea, 
the two scalos necessarily communicate with each other at the 
apex. 

These different bands or strips which compose the lamina 
spiralis, are called its Zones, and are termed Zona Ossea, Zona 
Coriacea, Zona Vesicularis, and Zona Membranacea. 

From what has been stated it follows that there are two cavi- 
ties in the cochlea, each of which continues throughout its whole 
extent. One begins at the vestibule; the other at the tympanum. 
But a membrane extended over the foramen rotundum separates 
this last from the tympanum. They communicate with each 



THE THREE SEMICIRCULAR CANALS. 431 

other at their terminations. From their origins they are denomi- 
nated Scala Vestibuli and Scala Tympani. 

As both the cochlea and the vestibule are filled with a fluid, 
it is evident that a vibration produced on the membrane of the 
foramen rotundum may be communicated through the two scala? 
to the vestibule. 

The three Semicircular Canals 

Are placed obliquely behind the vestibule. Their position is 
such that one is Superior, another Posterior, and the third Ex- 
terior. The superior and posterior are so placed that one extremity 
of each may be considered as internal and the other external. 
They unite at their internal extremities, which therefore form 
but one orifice in the vestibule. Their other extremities, being 
separated to a considerable distance, form each one orifice ; 
while the external canal, which is smaller than the others, opens 
by two orifices. 

Each of these canals is nearly of the same diameter, viz. 
rather more than two lines. 

At one of their extremities, each one of them has an enlarge- 
ment, which is called Ampulla; and there is no other variation 
of their diameters. 

The cavity of the labyrinth, thus complicated, is perforated 
by many small foramina, through which various nerves are 
transmitted. 

These foramina communicate with the large canal on the 
posterior side of the petrous bone, called Meatus Auditorius In- 
ternus; which continues very near to the basis of the cochlea, 
and transmits the seventh pair of nerves. 

The bottom of this cavity is divided by a ridge into two une- 
qual fossae; the uppermost of which is the least. 

In the Upper Fossa are two foramina; the anterior, which is 
the largest, serves to transmit the Portio dura, a part of the 
seventh pair, to be hereafter described, which passes through the 
petrous bone to the face. The posterior foramen forms a pit 
with a cribriform bottom, which admits nervous fibrillse to the 
vestibule. 



432 MEMBRANOUS LABYRINTH. 

The anterior part of the Inferior Fossa is also cribriform ; its 
perforations lead to the cochlea ; one of them, which passes 
through the modiolus to the infundibulum, is larger than the rest. 
The posterior part of this fossa is occupied by foramina, which 
pass to the vestibule and semicircular canals; but they are not 
so numerous as those which lead to the cochlea. 

Contents of the Labyrinth. 

This interesting cavity is lined throughout by a delicate mem- 
brane. It contains sacs and tubes, and a plexus of delicate 
nerves, which constitute a soft labyrinth within that which is 
composed of bone. 

In the cavity of the Vestibule are two sacs distinct from each 
other, and also from the lining membrane. 

One of these denominated Sacculus Sphericus, or Sacculus 
Vestibuli, is .situated partly in the Hemispherical Cavity of the 
vestibule, and has no direct communication with any other part. 

It contains a limpid fluid, and is said to have so much firm- 
ness, that when opened with the point of a lancet, it will retain 
its form. 

The other sac is situated partly in the depression called Semi- 
elliptical, nearly opposite to the foramen ovale: it is so trans- 
parent that it is sometimes seen with difficulty, and appears like 
a bubble of air in a fluid. All the membranous semicircular 
canals, which are soon to be described, communicate with it by 
each of their extremities : it has been called Alveus Communis 
by Scarpa, and Utriculus by Sommering. 

In the bony canals already described, are three Membranous 
Semicircular Canals, which resemble them in form. They have 
an ampulla at one extremity, as they arise from the sac above 
mentioned, and are cylindrical during the remainder of their 
course; they are transparent, and have smaller diameters than 
the bony canals, although they are rather longer. 

The Auditory Nerve. 

Upon this structure, viz. the Sacs in the Vestibule, the Mem- 
branous tubes in the Semicircular Canals, and the Lamina 



COCHLEA. 433 

Spiralis of the Cochlea, are expanded the fibres of the Auditory 
Nerve. 

This nerve, with the Portio Dura, and its appendage, the 
Portio Media, composes the seventh pair of nerves of the brain. 

It is called Portio Mollis, and is very distinct from the Portio 
Dura, although they pass together along the Meatus Auditorius 
Internus. 

Corresponding to the foramina and the cribriform structure of 
the bottom of the meatus auditorius internus, the Auditory Nerve 
passes into the labyrinth in branches, or fibrillar, of various sizes. 
One portion of them enters the vestibule, and has been traced 
upon the alveus or utriculus, and its internal surface; and also 
upon the semicircular membranous tubes. Another portion 
seems exclusively appropriated to a part of these tubes. And a 
third is spent upon the sacculus sphericus. 

These nervous fibres seem to terminate in a pulpy expansion 
on the internal surface of the aforesaid sacs and canals, in a way 
which has some analogy with the termination of the optic nerve. 

A large bundle of these fibrillar enters the cochlea at its base : 
and the largest of them passes through a foramen, mentioned 
before, along the centre of the modiolus to the infundibulum. 

These fibrillae divide most minutely, and passing between the 
plates of the Lamina Spiralis, as well as the other parts of the 
bony structure of the cochlea, at length form a plexus, which 
has the appearance of a pulpy membrane, that is extended over 
the whole of the lamina spiralis. Thus is the auditory nerve 
distributed. 

— The central portion of the modiolus, contains a great number 
of minute canals, and which is in consequence called by Scarpa 
the tractus spiralis foraminulosus. Into these the nerves of the 
cochlea enter, and pass out successively at right angles, between 
the two bony plates forming the zona ossea of the lamina spiralis, 
to be expanded on the membranous portion of the lamina. The 
nervous pulp is expanded in a naked state, and the neurilema 
which it throws off, forms, according to Breschet, the basis of 
the membranous structure of the lamina spiralis. — 

To complete the account of the labyrinth, it is to be observed 
vol. ii. 37 



434 



COCHLEA. 



that a pellucid fluid certainly exists in it, exterior to the sacs in 
the vestibule, and to the membranous semicircular canals ; so 
that the membranous labyrinth may be said to be immersed in 
a fluid. 

This fluid fills, also, the cochlea. 

Fig. 89.* 




vmm 



— A useful distinction has been made by many anatomists of 
the parts of the labyrinth or internal ear, into a bony labyrinth 

* Fig. 89, is a vertical section ofthc cochlea through its axis, in order to exhibit its 
internal structure, much magnified, a a a, Branch of the auditory nerve to the 
cochlea (nervus cochlearis), over which the veins are seen running and penetrating 
in small branches through the lamina spiralis. The arteries are not shown 
here, but they have the same course as the veins, b, Filaments of the nerve, 
lodged in the zona ossea of the cochlea, c c, Anastomoses of the filaments of the 
nerve with one another in the form of loops, in the zona media, d, The neurilema 
abandoning the nervous loops, in order to form, according to Brescbet, the zona 
membranosa. The blood-vessels are seen accompanying all these branches, e, 
A venous sinus, excavaled in the bone, at the outer margin of the zona membranosa. 
The venous sinus e, opens at the margin of the lamina spiralis, which divides the 
scala tympani below from the scala vestibuli above. Between the windings of the 
double tube, which resemble the turns of a circular pair of stairs, is seen a process 
of bony matter passing in to the modiolus. The bristle is passed in at the infundi- 
bulum, through the scala tympani, and brought out through the scala vestibuli, 
showing the communication of these cavities. — p. 



COCHLEA. 435 

and a membranous labyrinth. The bony labyrinth, consisting of 
the bony vestibule, cochlea, and semicircular canals, forms only 
the frame-work or walls to more important parts. The sacs of 
the vestibule, the membranous lining of the cochlea, and the mem- 
branous semicircular tubes, are parts upon which the auditory 
nerves and vessels are distributed, and are the parts immediately 
concerned in the production of hearing. The membranous 
cochlea, so far at least as has yet been observed, lines the internal 
face of the scala of the bony cochlea, and appears to serve as its 
periosteum as well as a field for the expansion of the cochleary 
division of the auditory nerve. The vestibule and the semicircu- 
lar canals have a periosteal lining membrane distinct from their 
membranous structure and from which the limpid fluid of the laby- 
rinth is secreted. The membranous sac of the vestibule, and the 
membranous canals, occupy but a small part of their respective 
bony cavities, with the walls of which, according to the recent 
researches of Breschet, they are only indirectly connected by 
the nerves and blood-vessels which enter their structure through 
foramina in the bony labyrinth. The limpid fluid alluded to, 
(p. 375,) called the lymph of Cotunnius, from the anatomist who 
first described it, is found not only filling the cavities of the mem- 
branous labyrinth, but likewise fills up completely the space 
between the membranous and bony vestibule, and the membra- 
nous and bony canals. It is asserted by Brugnone and Ribes, 
that the lymph but partly fills the cavity in its natural condition : 
but Breschet,* from elaborate researches in man and a variety 
of vertebrated animals, asserts this to be an error.f The mem- 
branous structure is afloat as it were in this fluid, and is affected 
by the slightest impulse communicated to the fluid, through the 
membrane closing the foramen rotundum and foramen ovale, 
with which the fluid is in contact. The endolymph is denser in 
fish than in land animals. M. E. Barruel has examined it che- 

* Rechcrches Anatomiques et Pathologiques sur l'Organsde l'Ouie, et sur 1'Au- 
dition, dans l'Momme et les Animaux Vertebres ; par G. Breschet. Mcmoires de 
l'Academie Royale de Medecine ; torn. v. 

f Cotugno and P. F. Meckel held the same opinions as Breschet. 



436 



ENDOLYMPH— PERILYMPH. 



mically in the great seal, (Squalus Cat. L.) He found it viscous 
and transparent, containing a matter floating in it, which when 
dried formed a calcareous powder. 

— For the sake of clearness of description, Breschet proposes to 
call the fluid within the membranous labyrinth the endolymph; 
that between it and the bony labyrinth the perilymph. The audi- 
tory nerves terminate in delicate villi, which project in the cavi- 
ties filled by the endolymph, and in order to give the sonorous 
impulse transmitted from without more effect upon the nerves, 
there is placed in the cavity of the labyrinth from one to three 
calcareous substances which are thrown into agitation by the im- 
pulse. These have been long known to exist in the ears of osse- 
ous fishes, as small concretions of carbonate of lime, see Fi».90. 

called otoliths;* and Bre- 
schet has found them inva- 
riably to exist, in the state of 
granular powder which he 
calls otoconie,-\ in man, the 
three upper classes of ver- 
tebrated animals, and in 
cartilaginous fishes. The 
cavity in which the peri- 
lymph is contained in the 
cochlea, vestibule and semi- 
circular canals, is continu- 
ous, so that an impulse trans- 
mitted through the mem- 
brane of the foramen ro- 
tundum, would pass along 
the scala tympani across 
the infundibulum, down the 
scala vestibuli, and be felt 
both in the vestibulum and semicircular canals. In the same 

* Ouc, cerot, ear ; x<floc, stone. f Otoc, kohc, ta>c, powder, dust, etc. 

t Fig. 90, Represents a magnified view of the bony labyrinth of the right side of 
the body, with the membranous labyrinth (consisting of semicircular tubes, me- 
dian or utricular sinus sometimes called sacculus ellipticus and sacculus sphericus), 
pulverulent concretions, and the termination of the nerves. The two scala of the 




CALCAREOUS CONCRETIONS IN THE LABYRINTH. 437 

manner the action of the chain of bones upon the foramen ovale, 
would be felt through the entire labyrinth. 
— It has been suggested that the two foramina, ovale and rotun- 
dum, are provided for the purpose of rendering more complete 
the transmission of the vibration of the membrana tympani ; one 
acted on by the chain of bones, the other by the air of the tym- 
panic cavity ; both at the same time causing movements in the 
lymph, at opposite points in the labyrinth, which should pass once 
through different portions of the labyrinth, agitate all the parts 
on which the nerves are spread, and finally neutralise each other, 
in the semicircular canals and in the scala of the cochlea, so as to 
prevent the repetition and reverberation of single sounds. 
— The calcareous concretions above alluded to, are found, in the 
mammiferae,only in thealveus communis and sacculusellipticus of 
Scarpa, in which the semicircular tubes open, and which Breschet 
calls the middle sinus. They form a small single granular mass. 
Opposite these concretions the auditory nervous filaments termi- 

cochlea are also seen, and their openings into the vestibule and into the cavity of the 
tympanum. The bony labyrinth is represented as cut open, showing the mem- 
branous labyrinth. All the parts marked with the asterisks (**) are filled with 
the lymph of Cotunnius. a, Ampulla of the anterior or semicircular canal, b, Am- 
pulla of the internal semicircular canal, c, Ampulla of the posterior semicircular 
canal, d, Anterior membranous semicircular canal, e, External membranous 
semicircular canal. /, Posterior membranous semicircular canal, g, Common 
membranous canal resulting from the junction of the anterior and posterior canals, 
d and/, h, Place where the semicircular canal opens into the utricular or median 
sinus, i, i, Utricular or median sinus, filling a great part of the vestibule, and 
exhibiting through its walls a mass of calcareous powder at h, (otoconie utricvlaire.) 
I, I, Sac containing also a mass of calcareous powder at m, (otoconie sacculaire.) 
n, Nervous fasciculus, forming an expansion, 0, on the ampulla of the anterior canal; 
another, ;>, on that of the external; and a third, q, on the sinus utriculosus. r, Ner- 
vous fasciculus distributed on the sac. v, Nervous fasciculus distributed on the 
posterior ampulla, s, s, Lamina spiralis, s, End of the lamina, forming its hamu- 
lus or hook, t, Commencement of the scala tympani near the fenestra rotunda, 
which is not shown here, u, Commencement of the scala vestibuli. x, Modiolus 
or column, round which is wound the lamina spiralis, y, y, Bristle engaged in the 
infundibulum (Helicotrome), by which the two scala communicate together at the 
top of the modiolus, z, Place where the modiolus is continuous at its summit, 
with the walls of the osseous labyrinth. 10, ic, ic, Membranous portion of the 
lamina spiralis. — p. 

3? * 



438 JACOBSON'S NERVOUS ANASTOMOSIS. 

nate in great number, and the prominent villi which they form 
seem even to reach the concretions. 

— Gregoire St. Hilaire and Breschet, have instituted compa- 
risons between the parts of the labyrinth which form the organ of 
hearing proper, and the parts contained in the globe of the eye. 
The endolymph they call the vitrine auditive, and compare it to the 
vitreous humour, in allowing the sonorous rays or impulses to 
pass through it, and in keeping distended the membranous la- 
byrinth upon which the nerves terminate, and which they con- 
sider analogous to the retina. The light calcareous concretions 
are, as they think, for the purpose of increasing the effect of the 
impulses, as the crystalline humour increases the effect of the 
luminous rays by concentrating them into a focus. Arnold and 
Tiedemann consider the membrana tympani as analogous in its 
office to the iris, regulating, by its state of tension or relaxation, 
the degree of impression made upon the nerves of hearing. The 
comparison is rendered more complete, by the recent discovery 
by Arnold, of an auricular ganglion, which is considered as an 
appendage of the sympathetic nervous system, and which, ac- 
cording to them, is the central regulator of the sympathetic, or 
instinctive movements of the membrana tympani, as the ophthal- 
mic ganglion is of that of the iris. 

Of Jacob son 's Anastomosis,* or the Nervous Plexus of the Tympa- 
num and the Auricular Ganglion of Arnold. 

— The cavity of the tympanum receives nerves from various 
sources, which communicate together upon the walls of that ca- 
vity so as to form a plexus, and which are chiefly spent upon the 
parts situated in the tympanic cavity. 
— This plexus is formed by branches from the great sympathetic, 



* The existence of this plexus was first made known by M. Jacobson, of Co- 
penhagen, who first traced an anastomosing: loop from the glossopharyngeal nerve 
through the cavity of the tympanum, which there left branches, and thence was 
reflected downwards to join the third branch of the fifth pair. Since then, the 
nerve has been shown to terminate, or arise in a ganglion, discovered by Arnold, 
of Zurich, on the lower surface of the third branch of the fifth pair of nerves, 
called auricular ganglion, ganglion oticum, ganglion maxillo-tymjianique. — p. 



AURICULAR OR OTIC GANGLION OF ARNOLD. 



439 



the glossopharyngeal, the trigeminal or fifth pair, the facial, the 
auricular ganglion, and the pneumogastric. 
—This plexus, see Fig. 91, is found on the outside of the walls of 
the cranium, and on the outer face of the inner wall of the cavity 
of the tympanum. It is found in all animals endowed with a 
tympanum: and in fishes that possess only an auditory bulb, 
formed by the labyrinth, it is found spread in a few filaments 
on the outer face of the bulb, the usual situation of the tympa- 
num in other animals. 

Fie. 91.* 




— Shortly after the glossopharyngeal nerve emerges from the 
jugular fossa, it forms a gangliform enlargement, called the 

* Fio-. 91 exhibits a view of the auricular ganglion of Arnold, and its connexions 
with surrounding parts . A, Right side of the cranium. B, petrous portion. C, Cri- 
briform plate of the ethmoid bone. D, Turbinated bone. E, Carotid artery. F, 
Internal jugular vein, u, otic ganglion, sending off its branches to the tympanum, 
, to the soft palate, and its descending twigs of communication, b, Ganglion of 
Meckel, or sphenopalatine ganglion, c, Ganglion of Gasser, or semilunar gan- 
glion of the fiah pair of nerves, d, Ophthalmic nerve, e, Superior maxillary 
nerve. /, Inferior maxillary nerve, g, Chorda tympani. h, Malleus, i, Incus. 
jfc, Glossopharyngeal nerve. I, Ganglion formed on this nerve, called ganglion of 
Andeisc/i or ganglion :>clrosum. m,m, Brandies from it through the lympauum to 
the auricular ganglion called Jacobson's Anastomosis, n, Branches of communi- 
cation between this nerve, and the carotid plexus and ganglion, o.—v. 



440 AURICULAR OR OTIC GANGLION. 

ganglion of Jlndersch, from the anatomist who first described it, 
or ganglion petroswn, from its proximity to the petrous bone. 
From this ganglion passes, upwards and forwards, the nerve of 
Jacobson, and enters a small canal, the orifice of which opens 
in the excavated border, which separates the carotid canal 
from the jugular sinus. The nerve emerges from the canal 
near the anterior border of the fenestra rotunda, traverses 
the promontory, comes in front of the foramen ovale, passes 
below the anterior part of the tensor tympani muscle, and 
curves forward between this muscle and the Vidian nerve, to 
terminate in the auricular ganglion of Arnold. 
— In the latter part of its course it is parallel with the proper 
nerve of the tensor tympani muscle, which comes off from the 
ganglion of Arnold. 

— This is the usual method of describing the course of this 
nerve, but we might, according to Breschet, with equal propriety 
adopt the views of Arnold, and consider it as arising from the 
ganglion, which is evidently the fact in regard to many of the in- 
ferior animals, as the nerve is largernear the ganglion, than in the 
tympanic cavity. As it enters the tympanum, it gives off one fila- 
ment to the fenestra rotunda and the mucous membrane surround- 
ing it, and another to the membrane surrounding the margin of the 
foramen ovale. Whilst in the bony structure of the promontory 
it gives off several filaments through canals in the bone; viz. 
several filaments of communication pass through the osseous wall 
of the carotid canal to unite with the carotid plexus of the sym- 
pathetic; others form a junction with the vidian or chorda tym- 
pani nerve. A filament from the pneumogastric (the tympanic) 
anastomoses with it, either before or after its entry into the cavity 
of the tympanum ; a filament is sent off in the direction of the 
Eustachian tube, and another branch is occasionally met with, be- 
tween this nerve and the portia dura, which Breschet is disposed 
to think is continuous with the pars media of the seventh pair of 
nerves. Many minute blood-vessels accompany these branches. 
See Fig. 91. 

— The auricular ganglion of Arnold, is small, though more 
than double the size of the ophthalmic, and is ash-coloured and 
pulpy like those of the sympathetic nerve. It is situated in ad- 



THE AaUEDUCTS. 44 J 

vance of the ganglion of Gasser, on the lower surface of the 
inferior maxillary nerve at the inner margin of the foramen 
ovale of the sphenoid bone. The existence of this ganglion may 
readily be detected by any one skilled in minute dissection. 
— It is united by short nervous roots, and cellular tissue to the 
third branch of the fifth pair of nerves. Besides the branches 
mentioned as coming from the auricular ganglion, Arnold, Bre- 
schet, and others, describe branches of communication which pass 
from it; one to the superior cervical ganglion of the sympathetic, 
along the tract of the arteria meningea magna, one which passes 
into the internal auditory meatus to anastomose with the auditory 
nerve, as well as other branches which unite with filaments of 
the fifth and facial nerves. I have not as yet been able to trace 
these filaments with satisfaction, and those who have attempted 
to follow minute n3rvous fibrils through bony parts can well ap- 
preciate the difficulties of the undertaking. The German anato- 
mists in general, consider this ganglion, as well as the ophthalmic, 
spheno-palatine, etc., as so many appendages or cranial termi- 
nations of the sympathetic nerve. — 

The Aqueducts. 

It is, probably, on account of this fluid, that two small canals 
exist ; which are called, after the anatomist who first suggested 
their use, the Aqueducts of Cotunnius.* 

One of these commences in the scala tympani of the coch- 
lea, near the foramen ovale; and terminates in the jugular fossa, 
by a small orifice, situated before the spine that separates the 
eighth pair of nerves from the internal jugular vein. It is called 
the Aqueduct of the Cochlea. 

The other originates in the vestibule, under the common ori- 
fice of the two canals, and terminates on the posterior surface of 
the petrous bone, by a small orifice, which is situated at some 
distance behind the meatus auditorius internus. It is called the 
Aqueduct of the Vestibule. 

— The aqueducts of the cochlea and vestibule are large in the 
foetus and during the growing period of the bone; and as Itard 
has first observed, become in old age extremely minute and often 

* See Sandiford's Thesaurus Dissertationum, &c. vol. i. 



442 COURSE OF THE PORTIO DURA. 

entirely obliterated. The external orifice of the aqueduct of the 
vestibule corresponds to a venous sinus (sinus petrosum), and that 
of the cochlea to the internal jugular veins. The researches of 
Brugnone and Ribes have shown conclusively that the aque- 
ducts are simple foramina for the introduction of veins. — 

To this account of the ear it ought to be added, that the 
Portio Dura, after entering into the petrous bone by the foramen 
in the upper fossa of the meatus auditorius internus, proceeds 
in a canal which is called the Aqueduct of Fallopius, through the 
bone, to the foramen stylo-mastoideum, on its inferior surface, 
where it emerges, and is distributed to the face. It is therefore 
called the Facial Nerve by some anatomists. 

In the course of this nerve from the meatus through the solid 
bone, it forms a remarkable angle, and then passes between the 
cochlea and the semicircular canals, to the foramen stylo- 
mastoideum. 

In this course it soon receives the Vidian nerve already men- 
tioned ; and it sends off the chorda tympani, immediately before 
it passes out at the foramen stylo-mastoideum. It also sends 
off small fibrils to the muscles of the bones of the ear. 

It has not been ascertained whether the portio dura, the Vi- 
dian nerve, and the chorda tympani, have any effect upon the 
function of hearing. 

The situation of those branches of the auditory nerve which are expanded 
in the vestibule and the semicircular canals, is somewhat different from 
the situation of those which are in the cochlea ; but it has not yet been 
ascertained how far their functions are different. 

The information on this subject derived from comparative anatomy, is very 
interesting; but, for want of more acquaintance with the state of this func- 
tion, in the different animals, no very decisive inferences have been drawn 
from it. 

The vestibule and semicircular canals occur much more frequently than 
the cochlea, which is to be found in few animals, if any, besides those of 
the classes of mammalia and of birds. It is therefore supposed necessary 
to that perfect state of hearing which the animals of these classes enjoy. 
But there remains a considerable difficulty on this subject; the cochlea in 
not, by any means, so perfect in birds as in quadrupeds; yet many birds 
appear to have clear perceptions of musical sounds, and some birds imitate 
articulate sounds with considerable accuracy. 



FUNCTIONS OF DIFFERENT PARTS OF THE LABYRINTH. 443 

That the impression which produces hearing is made on the nervous expan- 
sions in the Labyrinth, does not appear to be doubted by any one. The 
structure of the whole organ, and the analogy between it and the eye 
induce a strong belief that this is the case. 

This belief is confirmed by a dissection recorded by Mr. Haighton * in which 
Original Deafness was found to depend upon a quantity of cheese-like 
matter, which filled the whole labyrinth, and was attended with a con- 
siderable diminution of the size of the auditory nerve, while all the other 
parts of the organ were in a perfectly natural state. 

* See Memoirs of the Medical Society of London, vol. 3. 



444 



EXPLANATION OF PLATE XIII. 

Fig. 1. Shows the Lachrymal Canals, after the Common Teguments and 
Bones have been cut away. 

a, The lachrymal gland, b, The two puncta lachrymalia, from which the 
two lachrymal canals proceed to c, The lachrymal sac. d, The lachrymal 
duct, e, Its opening into the nose, f, The caruncula lachrymalis. g, The 
eyeball. 

Fig. 2. An Interior View of the Coats and Humours of the Eye. 

a a a a, The tunica sclerotica cut in four angles, and turned back, bbbb, 
The tunica choroides adhering to the inside of the sclerotica and the ciliary 
vessels are seen passing over — c c, The retina which covers the vitreous 
humour, d d, The ciliary processes which were continued from the choroid 
coat, e e, The iris, f, The pupil. 

Fig. 3. Shows the Optic Nerves, and Muscles of the Eye. 

a a, The two optic nerves before they meet, b, The two optic nerves 
conjoined, c, The right optic nerve, d, Musculus attollens palpebral su- 
perioris. e, Attollens oculi. f, Abductor, g g, Obliquus superior, or tro- 
chlearis. h, Abductor, i, The eyeball. 

Fig. 4. Shows the Eyeball with its Muscles. 

a, The optic nerve, b, Musculus trochlearis. c. Part of the os frontis, 
to which the trochlea or pulley is fixed through which, — d, The tendons of 
the trochlearis pass, e, Attollens oculi. f, Adductor oculi. g, Abductor 
oculi. h, Obliquus inferior, i, Part of the superior maxillary bone to 
which it is fixed, k, The eyeball. 

Fig. 5. Represents the Nerves and Muscles of the Right Eye, after part of 
the Bones of the orbit have been cut away. 

A, The eyeball. B, The lachrymal gland. C, Musculus abductor oculi. 
D, Attollens. E, Levator palpebral superioris. F, Depressor oculi. G, 
Abductor. H, Obliquus superior, with its pulley. I, Its insertion into the 
sclerotic coat. K, Part of the obliquus inferior. L, The anterior part of 
the os frontis, cut. M, The crista galli of the ethmoid bone. N, The pos- 
terior part of the sphenoid bone. 0, The transverse spinous process of the 
sphenoid bone. P, The carotid artery, denuded where it passes through 
the bones. Q, The carotid artery within the cranium. R, The ocular 
artery. 

Nerves. — a a, The optic nerve, — b, The third pair, c, Its joining with 
a branch of the first branch of the fifth pair, to form 1, — The lenticular gan- 
glion, which sends off the ciliary nerves, d. e e, The fourth pair, f, The 
trunk of the fifth pair, g, The first branch of the fifth pair, named ophthal- 
mic, h, The frontal branch of it. i, Its ciliary branches, along with which 



EXPLANATION OF PLATE XIII. 445 

the nasal twig is sent to the nose, k, Its branch to the lachrymal gland. 
1, The lenticular ganglion, m, The second branch of the fifth pair, named 
superior maxillary, n, The third branch of the fifth pair, named inferior 
maxillary, o, The sixth pair of nerves — which sends off p, The beginning 
of the great sympathetic, q, The remainder of the sixth pair, spent on c, 
The abductor oculi. 

Fig. 6. Represents the head of a youth, where the upper part of the cra- 
nium is sawed off, — to show the upper part of the brain, covered by the 
pia mater, the vessels of which are minutely filled with wax. 

A. A, The cut edges of the upper part of the cranium. B, The two tables 
and intermediate diploe. B B, The two hemispheres of the cerebrum. CC, 
The incisure made by the falx. D, Part of the tentorium cerebelli super- 
expansum. E, Part of the falx, which is fixed to the crista galli. 

Fig. 7. Represents the parts of the External Ear, with the Parotid Gland 

and its Duct. 

a a, The helix, b, The antihelix. c, The antitragus. d, The tragus. 

e, The lobe of the ear. f, The cavitas innominata. g, The scapha. h, 
The concha, i i, The parotid gland, k, A lymphatic gland, which is often 
found before the tragus. 1, The duct of the parotid gland, m, Its opening 
into the mouth. 

Fig. 8. A view of the posterior part of the external Ear, meatus auditorius, 
the tympanum with its small bones, and Eustachian tube, of the right 
side. 

a, The back part of the meatus, with the small ceruminous glands, b, 
The incus, c, Malleus, d, The chorda tympani. e, Membrana tympani. 

f, The Eustachian tube, g, Its mouth from the fauces. 

Fig. 9. Represents the anterior part of the right external Ear, the cavity of 
• the tympanum — its small bones, cochlea, and semicircular canals. 

a, The malleus, b, Incus, with its long leg resting upon the stapes, c, 
Membrana tympani. d, e, The Eustachian tube covered by part of — f f, 
The musculus circumflexus palati. 1, 2, 3, The semicircular canals. 4, 
The vestibule. 5, The cochlea. 6, The portio mollis of the seventh pair 
of nerves. 

Fig. 10. Shows the Muscles which compose the fleshy substance of the 

Tongue. 

a a. The tip of the tongue, with some of the papillae minima^, b, The 
root of the tongue, c, Part of the membrane of the tongue, which covered 
the epiglottis, d d, Part of the musculus hyo-glossus. e, The lingualis. 
f, Genio-glossus. g g, Part of the stylo-glossus. 

vol. ii. 38 



PART XI. 
OF THE NERVES. 



The nerves are those whitish cords which pass from the brain 
and spinal marrow to the various parts of the body. 

A general account of their origin is contained in the description 
of the basis of the brain and of the spinal marrow,* which may 
be considered as introductory to the present subject. 

The nerves, in general, appear to be bundles or fasciculi of 
small cords, each of which is composed of a series of fibres that 
are still smaller. These fibres consist of medullary matter, 
which is derived from the brain and spinal marrow, and is en- 
closed in a membranous sheath that appears to arise from the 
pia mater. The smaller the fibre, the more delicate is the mem- 
brane which invests it. 

As the nerves proceed from the brain and spinal marrow, 
through the foramina of the cranium and the spine, they are 
enclosed in a sheath formed by the dura mater; but when they 
arrive at the exterior extremities of the foramina in those bones, 
this coat, derived from the dura mater, appears to separate into 
two lamina. The exterior lamen combines with the periosteum, 
and the interior continues to invest the nerve, but seems to change 
immediately into cellular substance; so that the exterior coat of 
the nerves may be regarded as composed of cellular mem- 
brane, which is continued from the sheath derived from the dura 
mater. 

It has been supposed that the membrane which forms the 
sheaths for the medullary fibrils of which the nerves are com- 

* See volume ii. page 354. 



GENERAL STRUCTURE OF NERVES. 447 

posed, is of a peculiar nature; but it appears to be derived from 
the pia mater, investing the brain and the spinal marrow. It is 
very vascular.* 

The ramification of a nerve is simply the separation of some 
fibres from the general fasciculus. The branch commonly forms 
an acute angle with the main trunk. 

The course of these branches from their origin to their termi- 
nation is generally as straight as possible. 

When the nervous cords are examined in an animal recently 
dead, there is an appearance of white lines arranged in a trans- 
verse or spiral direction. The cause of this appearance is not 
well understood. 

In various parts of the body networks are formed by the 
combination of different nerves or the branches of nerves. In 
those instances the branches of one nerve unite with those of 
another, and form new branches. These new branches again 
divide, and their ramifications unite with other new ramifications 
to form other new trunks. These new trunks divide again, and 
form new combinations in the same way. 

The trunks last formed proceed to the different parts of the 
body, as other nerves do which arise immediately from the brain. 

These combinations are denominated Plexuses. There are 
several of them in the cavities of the abdomen and thorax, formed 
by the ramifications of the par vagum and the sympathetic 
nerves. The four lower cervical, and the first dorsal nerve, form 
a very remarkable plexus of this kind, which extends from the 
side of the neck to the axilla, and forms the nerves of the arm. 
The lumbar nerves form a similar plexus, although not so com- 
plex, from which the crural nerve arises. The anterior nerves 
of the sacrum also unite for the formation of the great sciatic 
nerve. 

* Several authors have written professedly on the structure of the nerves, viz. 
Monro, in his " Observations on the Structure and Functions of the Nervous Sys- 
tem." — Bichat, "Anatomie Generale." — Fontana, "Treatise on the Poison of the 
Viper." — Reil, " Exercitationes Anatomicse." — Scarpa, " Annotationes Academi- 
cs)." — Prochaska, " De Structura Nervorum." 

I regret that it has not been in my power to procure Reil, Prochaska, or Scarpa. 



448 STRUCTURE OF NERVES. 

It appears to be clearly ascertained, that the great object of 
this peculiar arrangement is the combination of nervous fibres 
from many different sources, in each of the nerves, which are 
distributed to any organ. Thus, the smaller nerves of the arm, 
that are distributed to the different parts, are not to be regarded 
simply as branches of any one of the five nerves which are 
appropriated to the upper extremity, but as composed of fibres 
which are derived from each of them. 

Many of the nerves are enlarged in particular places, so as 
to form small circumscribed tumours, which are denominated 
Ganglions. 

These Ganglions are generally of a reddish colour. By very 
dexterous management, they can be shown to consist of a texture 
of fibres. The larger cords which compose the nerve, seem 
suddenly to be resolved into the small fibres, of which they 
consist. These small fibres, after proceeding separately a greater 
or lesser distance, according to the size of the ganglion, and 
changing their relative situation, are again combined in cords, 
which recompose the nerve. 

These fibres appear to be surrounded by a fine cellular sub- 
stance, which is vascular, moist, and soft. It is asserted that, in 
fat subjects, an oily substance, resembling fat; and in hydropic 
subjects, a serous fluid has been found in this texture. 

Ganglions are often connected with but one nerve, which 
seems to enter at one extremity and go out at the other. But 
they frequently receive additional branches from other nerves, 
and send off additional branches to parts different from those to 
which their principal nerves are directed. When connected 
with but one nerve, they have been called simple ganglions: 
when they receive and give off additional branches, they are 
denominated compound ganglions. It does not appear that there 
is any important difference in their structure, in these cases. 

The simple ganglions occur in the nerves of the spinal 
marrow — the posterior fasciculus of the nerves having always 
formed a ganglion before it is joined to the anterior fasciculus. 
The sympathetic nerve, throughout its whole extent, forms com- 
pound ganglions. 



NERVES OF THE BRAIN. 449 

The use of this particular structure does not appear to be 
perfectly known. It seems, however, certain, that the different 
fibres— (of which the nerves forming ganglions are composed)— 
are blended together and arranged in a manner different from 
that in which they were arranged before the nerve entered the 
ganglion. 

It ou<*ht to be observed, that the combination of nervous 
fibrillae, so as to bring together those fibrils which originally 
belonged to different cords, seems to have been kept in view 
throughout the whole arrangement of the nervous system. It is 
not only in the plexus and the ganglion that this appears, but, 
also, in some of the larger nerves ; for in them the fibres which 
form the cords that compose the nerve, instead of running pa- 
rallel to each other, along the whole extent of the nerve, form a 
species of plexus in their course, separating from the fibres with 
which they were originally combined, and uniting with the fibres 
of other cords ; as in other cases of plexus.* 

There have been doubts respecting the possibility of a repro- 
duction of the substance of the nerves when it has been destroyed ; 
but it appears to have been clearly proved by the experiments 
of Mr. Haighton, that a reproduction does really take place.f 

Nine pair of nerves proceed from the brain through the fora- 
mina of the cranium. They are called Nerves of the Brain, or 
Cerebral Nerves. One pair passes off between the cranium and 
the spine, which is called Sub-Occipital Twenty-nine or thirty 
pair pass through the foramina of the spine: they are denomi- 
nated Cervical, Dorsal, Lumbar, and Sacral, from the bones with 
which they are respectively connected. There are seven pair of 
cervical nerves, twelve dorsal, five lumbar, and five or six sacral 
— amounting, with the nerves of the brain, to thirty-nine or forty 
pair. 

Nerves of the Brain. 
The nerves which go off from the brain and medulla oblon- 

* See Monro's Observations on the Structure and Functions of the Nervous 
System. Piute xviii. 

t See London Philosophical Transactions, for 1795, Part I. 

38* 



450 FIRST PAIR OF NERVES. 

gata are named numerically, according to the order in which 
they occur, beginning with the anterior. They also have other 
names, which generally are expressive of the functions of the 
different parts to which they are distributed. 

Those which go to the nose are anterior to all the others, and 
are, therefore, denominated 

The First Pair, or the Olfactory Nerves. 

They arise by three delicate white fibres from the under and 
posterior part of the anterior lobes of the brain, being derived 
from the Corpora Striata. They proceed forward to the depres- 
sion on the cribriform plate of the ethmoid bone, on each side 
of the crista galli. The upper surface occupies a small sulcus 
formed by the convolutions of the lower surface of the brain, 
and, therefore, has a longitudinal ridge on it. The lower sur- 
face is flat. Their texture is like that of the medullary part of 
the brain. 

On each side of the crista galli each of them forms a pulpy 
enlargement of a brownish colour, which is called the bulb, and 
has been considered as a ganglion. 

From this bulb many fine and delicate cords go off, which 
proceed through the dura mater and the foramina of the cribri- 
form plate to the Schneiderian membrane. — These ramifications 
of the olfactory nerve seem to receive a coat from the dura 
mater, as they are much more firm after they have passed 
through it. They appear to be arranged in two rows as they 
proceed from the ethmoid bone — one running near to the septum, 
and the other to the opposite surface of the ethmoid bone.* 

The Second Pair, or the Optic Nerves, 

Originate from the Thalami Nervorum Opticorum, and appear 
on the external and lower surface of the brain, on each side of 
the sella turcica. 

Each of them seems like a chord of medullary matter enclosed 
in a coat derived from the pia mater, and has not the fascicu- 
lated appearance of the other nerves. The medullary matter, 

" See Fig. 91, page 439. 



8EC0ND AND THIRD PAIR OF NERVES. 45J 

however, appears to be divided by processes that pass through 
it, which are derived from the coat of the nerve. 

They proceed obliquely forward and inward, on each side of 
the sella turcica, in contact with the brownish cineritious sub- 
stance, in which the infundibulum and the corpora albicantia of 
Willis are situated.* Anterior to this substance they come in 
contact with each other, and again separate, in such a way, 
that it is an undecided question whether they decussate each 
other, or whether each forms an angle, and is in contact with 
the other at the angle. 

From this place of contact, each nerve proceeds to its respec- 
tive foramen opticum, where it receives a coat from the dura 
mater, which extends with it to the eye, as has been described 
in the account of that organ. 

The Third Pair of Nerves 

Are sometimes called Motores Oculorum, in consequence of 
their distribution to several muscles of the eye. They arise at 
the inside of the crura cerebri, and make their appearance on 
the basis of the brain, at the anterior part of the pons Varolii. 

They originate by numerous threads, which soon unite so as 
to form a cord, which passes through the dura mater, on each 
side of the posterior clinoid process, and continues through the 
cavernous sinus, and the foramen lacerum, to the orbit of the eye. 

Before this nerve enters the orbit it generally divides into two 
branches which are situated one above the other. The Upper- 
most Branch is spent principally upon the rectus superior muscle 
of the eye, but sends a twig to the levator palpebral The Infe- 
rior Branch is distributed to two of the recti muscles, viz. the 
internus and the inferior, and also to the inferior oblique. It 
likewise sends a twig to a small ganglion in the orbit, called the 
Lenticular or Ophthalmic Ganglion,] from which proceed the 
fine nervous fibres that perforate the sclerotic coat.J 

* See vol. ii. page 352. 

t This ganglion, which is considered as the smallest in the body, lies on the out- 
side of (he optic nerve, near its entrance into the orbit, and is generally surrounded 
by soft adipose matter. { See vol. ii. page 381. 



452 FOURTH AND FIFTH TAIR OF NERVES. 

The Fourth Pair of Nerves, 

Are called the Pathetic, in consequence of the expression of 
the countenance produced by the action of the muscle on which 
they are spent. They arise from the side of the valve of the 
brain, below and behind the Tubercula Quadrigemina,* and are 
so small that they appear like sewing thread. They proceed 
round the crura of the cerebrum, and appear on the surface be- 
tween the pons Varolii and the middle lobes of the brain. They 
proceed along the edge of the tentorium, which they perforate, 
and passing through the upper part of the cavernous sinus, enter 
the orbit by the foramina lacera. They are exclusively appro- 
priated to the Superior Oblique, or Trochlearis muscle. 

The Fifth Pair of Nerves 

Are called Trigeminus, because each nerve divides into three 
great branches. 

These nerves arise from the crura of the cerebellum, where 
they unite to the pons Varolii by distinct fibres, which are con- 
nected so as to form a cord or nerve, that is larger than any 
other nerve of the brain. In many subjects this cord seems par- 
tially divided into two portions, the anterior of which is much 
smaller than the posterior, and appears softer at its origin. 

It passes into a short canal formed by the dura mater, near 
the anterior extremity of the petrous portion of the temporal 
bone, at a small distance below the edge of the tentorium. It 
is perfectly loose and free from adhesion to the surface of this 
canal ; but it soon passes out of it under the dura mater, and 
then adheres to that membrane. After leaving the canal, it ex- 
pands like a fan, but still consists of fine fibres, which have 
some firmness. It is said that there are seventy or eighty of 
these fibres in the expansion, but they appear to be more numer- 
ous. Round the circumference of the expansion is a substance 
of a brownish colour, into which the fibres enter. This is the 
Semilunar Ganglion, or the Ganglion of Gasser, and from it the 
three nerves go off. 

* See vol. ii. page 356. 



OPHTHALMIC NERVE. 453 

These nerves pass off from the convex side of the ganglion, 
and are denominated the Ophthalmic, the Superior Maxillary, 
and the Inferior Maxillary. 

The Ophthalmic Nerve 

Passes into the orbit of the eye through the foramen lacerum : 
it there divides into several branches, which are called, from their 
distribution, the Frontal or Supra Orbitar, the Nasal and the 
Lachrymal. 

The Frontal or Supra Orbitar branch proceeds forward in the 
upper part of the orbit, exterior to the membrane which lines it, 
and divides into two ramifications. One of these is small, and 
passes out of the orbit near the pulley of the superior oblique, to 
be spent upon the orbicularis muscle and the contiguous parts. 

The other ramification passes through the supra orbitary 
foramen, or through the notch, which is in the place of that 
foramen, and divides into a number of twigs, some of which pass 
transversely towards the side of the head, and communicate 
with twigs from the portio dura. Most of the others extend up- 
wards on the head. Some are distributed to the anterior part of 
the occipito-frontalis muscle, and the integuments of the fore- 
head; others are spent upon the upper portion of the scalp. 
Some of the extreme parts of these ramifications also communi- 
cate with the portio dura. 

The Nasal Branch proceeds obliquely forward towards the 
inner side of the orbit, and sends a twig, in its course, to the len- 
ticular ganglion. It also sends off some small twigs, to join the 
ciliary nerves which go from the ganglion. On the inside of the 
orbit, a branch leaves it, which proceeds through the Foramen 
Orbitare Internum Anterius to the cavity of the cranium, and 
passes a small distance upon the cribriform plate of the ethmoid 
bone, under the dura mater, to a fissure in the said plate near the 
crista galli, through which it proceeds into the cavity of the nose. 
Here it divides into twigs, some of which pass on the septum near 
its anterior edge, and terminate on the integuments at the end of 
the nose, while others pass down on the inferior turbinated bone. 

After parting with the ramifications to the nose, the remainder 



454 SUPERIOR MAXILLARY NERVE, 

of the nasal branch continues to the internal canthus of the eye, 
and sends twigs to the lachrymal sac, the caruncula lachrymalis, 
the eyelids, and the exterior surface of the upper part of the nose. 
The Lachrymal Branch proceeds obliquely forward and out- 
wards, towards the lachrymal gland. In its course, it sends off 
a twig, which passes through the spheno-maxillary fissure, and 
communicates with a twig of the upper maxillary nerve, and one 
or more twigs that pass to foramina in the malar bone. The 
main branch passes to the lachrymal gland, and some twigs 
continue beyond it to the contiguous parts. 

The Superior Maxillary Nerve. 

The second branch of the fifth pair is examined with great 
difficulty on account of its peculiar situation. It proceeds from 
the semilunar ganglion, and passes through the foramen rotun- 
dum of the sphenoid bone into the upper part of the zygomatic 
fossa. In this situation it sends a twig to the orbit by the spheno- 
maxillary fissure, and a branch, called the Infra Orbitar, which 
appears like the main nerve, as it preserves a similar direction, 
to the infra orbitar canal. At the same place it sends down- 
wards two branches, which unite together almost immediately 
after their origin, and, as soon as they have united, enlarge into 
a ganglion.* The ganglion is called the Spheno-Palatine, or 
Ganglion of Meckel It is rather of a triangular figure, and lies 
very near the spheno-palatine foramen. It gives off a posterior 
branch, which passes through the pterygoid foramen to the 
cavity of the cranium : some branches which proceed through 
the spheno-palatine foramen to the nose, and are called the 
Spheno-Palatine or Lateral Nasal Nerves : and an inferior branch 
that proceeds through the posterior palatine canal, and is called 
the Palatine Nerve. 

The small branch, which was first mentioned, as going to the 
orbit by the spheno-maxillary fissure, divides into two ramifica- 
tions. One of them unites with a twig of the lachrymal branch 
above mentioned, and passes out of the orbit, through a foramen 

* Sometimes a single branch passes downwards instead of two ; but it forms a 
ganglion in the same place, 



OR SECOND BRANCH OP THE FIFTH PAIR. 455 

in the malar bone, to the face, where it is distributed. The other 
passes also through a foramen of the malar bone, into the tempo- 
ral fossa, and, after uniting with twigs from the Inferior Maxil- 
lary Nerve, proceeds backwards and perforates the aponeurosis 
of the temporal muscle, to terminate on the integuments of the 
temporal region. 

Before the Infra Orbitar branch enters the canal of that name, 
it sends off two twigs, called Posterior Dental Nerves, which pass 
downwards on the tuberosity of the upper maxillary bone, and 
enter into small canals in that bone, that are situated behind the 
antrum maxillare. They subdivide into fine twigs that proceed 
forward to the alveoli of three or four of the last molar teeth, 
and penetrate each of the roots by a cavity at its extremity. 
Twigs also proceed from these nerves to the posterior part of 
the gums and buccinator muscle. 

After the posterior dental nerves have left it, the Infra Orbitar 
nerve proceeds forwards in the canal of that name ; and near 
the extremity of it, gives off the anterior dental nerve, which 
accompanies it for some distance, and then proceeds downwards 
in a canal in the bone anterior to the antrum maxillare. In its 
course this nerve divides into many fibres, which pass to the 
roots of the incisor, canine, and small molar teeth, each in its 
proper canal. These dental branches sometimes pass in the 
antrum maxillare between the lining membrane and the bones. 
The Infra Orbitar nerve passes out of the foramen upon the 
cheek, and divides into several branches of considerable size, 
which are distributed on the face from the side of the nose to the 
back of the cheek, and also upon the under eyelid and the 
upper lip. 

The Pterygoid Nerve, or posterior branch, passes backwards, 
from the ganglion to a canal in the base of the pterygoid process 
of the os sphenoides, and proceeds through it. After leaving 
this canal, it passes through a substance almost as firm as carti- 
lage, which closes the anterior foramen lacerum, at the basis of 
the cranium, and divides into two branches. The smallest of 
them, called the Vidian Nerve, proceeds with a small artery to 
the small foramen, or Hiatus Fallopii, on the anterior side of the 



456 SUPERIOR MAXILLARY NERVE. 

petrous portion of the temporal bone, and continues, through a 
small canal, to join the portio dura of the seventh pair in the 
larger canal, called the Aqueduct of Fallopius, at the first turn in 
that canal.* The other branch of the pterygoid nerve proceeds 
to the foramen caroticum, and passes through it, with a twig of 
the sixth pair, to join the first cervical ganglion of the Intercostal 
Nerve. 

The Spheno-Palatine, or Lateral Nasal Nerves, consist of se- 
veral branches which pass from the spheno-palatine ganglion 
through the spheno-palatine foramen into the nose. Some of 
them are distributed to that part of the pituitary membrane, 
which is above the upper meatus, and others to the part which 
is immediately below it. Some of the branches which thus enter 
the nose are spread upon the septum; one among them extends 
upon it, downwards and forwards, to the anterior part of the pa- 
latine process of the upper maxillary bone, where it enters into 
the foramen incisivum, and terminates in a papilla in the roof of 
the mouth.f 

The Palatine Branch proceeds through the canal formed by 
the upper maxillary and palate bones, to the roof of the mouth 
and soft palate. Soon after its origin, it sends off a twig which 
proceeds down a small canal that is behind it. It also sends off, 
as it proceeds downwards, several twigs to that part of the mem- 
brane of the nose which covers the inferior turbinated bone. 
When it arrives at the roof of the mouth, it divides into several 
branches which run forwards, and are distributed to the mem- 
brane which lines the roof of the mouth. Some of its branches 
pass to the soft palate, the uvula, and the tonsils; small filaments 
pass into the back'part of the upper jaw. 



* The late Mr. John Hunter believed that this nerve parts from the portio dura 
at the lower end of the aqueduct, and is the chorda tyrnpani. 

t The curious distribution of this nerve appears to have been known to the late 
John Hunter, and also to Cotunnius ; but it is minutely described by Scarpa, and 
is delineated by Sommering in his plate of the nose. — See "Observations on cer- 
tain parts of the Animal Economy," by J. Hunter, page 219, and also Scarpa" De 
Organo Olfuctus." In this last are some interesting observations relative to the 
ducts of Steno. 



INFERIOR MAXILLARY NERVE. 457 

The Inferior Maxillary Nerve, or the Third Branch of the Fifth 

Pair, 

Passes through the foramen ovale into the zygomatic fossa, 
and divides into two branches, one of which sends ramifications 
to many of the contiguous muscles, as the temporal, the mas- 
seter, the buccinator, the pterygoid ; and, also, to the anterior 
part of the ear and the side of the head. The other branch 
passes between the pterygoid muscles, and divides into two 
ramifications, one of which proceeds to the tongue, and is called 
the Lingual or Gustatory, while the other passes into the canal 
of the lower jaw. 

The Lingual Nerve proceeds between the pterygoid muscles, 
and, in its course, is joined by the chorda tympani. It continues 
forward between the maxillary gland and the lining membrane 
of the mouth; and passes near the excretory duct of that gland, 
above the mylo-hyoideus and the sublingual gland to the under 
side of the tongue, near the point: it then divides into a number 
of branches which enter into that body between the genio-hyoi- 
deus and lingualis muscles. This nerve has been supposed to be 
particularly concerned in the function of taste, because many of 
its branches continue to the upper surface of the tongue, espe- 
cially near the point. In its course it has a communication with 
the ninth pair of nerves, and sends twigs to the membrane of 
the mouth and gums, and the contiguous parts. 

After parting with the lingual nerve, the inferior maxillary 
continues to the upper and posterior orifice of the canal in the 
lower jaw. Before it enters this canal it sends a branch to the 
sub-maxillary gland, and to the muscles under the jaw. It then 
enters the canal, attended by blood-vessels, and proceeds along it 
to the anterior maxillary foramen, on the side of the chin, through 
which it passes out. In this course it sends twigs to the sockets 
of the teeth, and generally supplies all the large and one of the 
small grinders. Before it leaves the jaw it sends a branch for- 
ward, which supplies the remaining teeth on the side to which it 
belongs. After passing out, through the anterior foramen, it is 

vol. ii. 39 



458 SIXTH PAIR OF NERVES. 

spent upon the muscles and integuments of the front of the cheek, 
the chin and the under lip. 

The Sixth Pair of Nerves, 

Are called Motores Externi. They arise from the commence- 
ment of the medulla oblongata, and proceed forward under the 
pons Varolii. They proceed through the dura mater on the in- 
side of the fifth pair, and appear to pass through the cavernous 
sinuses, but are enclosed in sheaths of cellular membrane while 
they are in those sinuses. When in this situation they are near 
the carotid arteries, and each nerve sends off one or more very 
fine twigs, which being joined by a twig from the pterygoid 
branch of the fifth pair, accompany the carotid artery through 
the carotid canal, and then unite themselves to the upper ex- 
tremity of the upper cervical ganglion of the intercostal nerve. 

The sixth pair afterwards pass into the orbit of the eye, each 
through the foramen lacerum of its respective side, and is spent 
upon the Rectus Externus or Abductor muscle of the eye. 

The Seventh Pair of Nerves 

Comprises two distinct cords, which have very different des- 
tinations; and have, therefore, been considered as different 
nerves, by several anatomists. One of these cords is appropri- 
ated to the interior of the ear, and is the proper Auditory Nerve. 
The other is principally spent upon the face, and, therefore, has 
been called the Facial. They have, however, more frequently 
been denominated the Seventh Pair, and distinguished from each 
other, in consequence of a great difference in their texture, by 
the appellations of Portio Dura and Portio Mollis. 

These two cords pass off nearly in contact with each other, 
from the side of the upper part of the Medulla Oblongata, where 
it is in contact with the pons Varolii; but the Portio Mollis can 
be traced to the fourth ventricle, while the Portio Dura is seen 
to rise from the union of the pons Varolii with the medulla ob- 
longata and the crura cerebelli. The Portio Dura, at its origin, 
is on the inside of the Portio Mollis. Between these cords are 



SEVENTH PAIR OF NERVES.— PORTIO DURA. 459 

one or more small fibres, called Portio Media, which seem to 
originate very near them, and finally unite with the Portio Dura. 
Each of the seventh pair of nerves, thus composed, proceeds 
from its origin to the meatus auditorius internus of the tempo- 
ral bone; and the portio mollis divides into fasciculi, which pro- 
ceed to the different parts of the organ of hearing in the manner 
described in the account of the ear.* 

The Portio Dura enters an orifice at the upper and anterior 
part of the end or bottom of the Meatus Auditorius Internus. 
This orifice is the commencement of a canal, which has been 
called the Aqueduct of Fallopius, and proceeds from the Meatus 
Auditorius Internus to the external foramen, between the mastoid 
and styloid processes at the basis of the cranium. This canal 
first curves backwards and outwards, near to the upper surface 
of the petrous bone, then forms an acute angle, and proceeds, 
(backwards and downwards,) to the stylo-mastoid foramen, pass- 
ing very near the cavity of the tympanum in its course. 

The Portio Dura, as it passes into the canal from the meatus 
internus, seems to receive an investment from the dura mater. 
It fills up the canal, but does not appear to be compressed. Near 
the angle it is joined by the twig of the Vidian nerve, which 
proceeds from the pterygoid branch of the fifth pair, and enters 
the petrous bone by the small foramen innominatum on its ante- 
rior surface. In its course through the canal it sends off some 
very small twigs to the muscles and appurtenances of the small 
bones of the ear, and to the mastoid cells; and, when it has ar- 
rived almost at the end of the canal, it sends off in a retrograde 
direction, a small branch which proceeds into the cavity of the 
tympanum, (entering it by a foramen near the base of the pyra- 
mid,) and crosses the upper part of it, near the membrana 
tympani, between the long processes of the Malleus and Incus. 
This twig is the Chorda Tympani; it proceeds from the cavity 
by a fissure on the outside of the Eustachian tube, to join the 
lingual branch of the fifth pair, as has been already mentioned.f 

* See vol. ii. p. 432. 

t The late John Hunter believed that the chorda tympani is merely a continua- 
tion of the twig of the pterygoid branch which joins the portio dura above. — See 
Observations on certain parts of the Animal Economy, page 220. 



460 EIGHTH PAIR OF NERVES. 

The Portio Dura, after passing out of the Foramen Stylo-Mas- 
toideum, is situated behind and within the parotid gland. Here 
it gives small twigs to the back of the ear and head, and to the 
digastric and stylo-hyoideus muscles. It perforates the gland 
after sending filaments to it, and then divides into branches which 
are arranged in such a manner that they constitute what has 
been called the Pes Anserlnus. 

To describe the various branches in this expansion would be 
more laborious than useful. Some of them are spread upon the 
temple and the upper part of the side of the head, and unite with 
the supra-orbitar branches of the ophthalmic nerve. Some pass 
above and below the eye, and are distributed to the orbicularis 
muscle, and communicate with nervous twigs that pass through 
foramina in the malar bone, &c. Some large branches pass 
transversely. These cross the masseter muscle, and divide into 
ramifications which are spent upon the cheek and the side of the 
nose and lips, and communicate with the small branches of the 
superior maxillary nerve. 

A large number of branches pass downwards. Many of them 
incline forwards, and are spent on the soft parts about the under 
jaw ; while others proceed below the jaw to the superficial 
muscles and integuments of the upper part of the neck, com- 
municating with the branches of the contiguous nerves.* 

The Eighth Pair of Nerves 

Are very frequently denominated the Par Vagum, on account 
of their very extensive distribution. 

They arise from those portions of the medulla oblongata 
which are denominated the Corpora Olivaria. Each nerve con- 
sists of a cord, which is anterior, and called the Glosso- Pharyn- 
geal; and of a considerable number of small filaments, which 
arise separately, but unite and form another cord, the proper 

* A most minute and laboured description of the nerves of the face was pub- 
lished by the celebrated Meckel, in the seventh volume of Memoirs of the Royal 
Academy of Sciences of Berlin, for the year 1751, accompanied with a plate, 
exhibiting the side of the head, of three times the natural size. This is republished 
in the Collection Academiquc: Partie Etrangere. — Tom. viii. 



GLOSSOPHARYNGEAL. 461 

Par Vagum. Associated with these is a third cord, called the 
Spinal or Accessory Nerve of Willis, which originates in the 
great canal of the spine, and, passing up into the cavity of the 
cranium, goes out of it with these nerves through the foramen 
lacerum. 

The two first mentioned nerves proceed from their origin to 
the posterior foramen lacerum, and pass through it with the 
Internal Jugular vein, — being separated from the vein by a small 
process of bone. They are also separated from each other by a 
small process of the dura mater. In the foramen they are very 
close to each other; but soon after they have passed through it, 
they separate and proceed towards their different destinations. 

The Glosso-Pharyngeal proceeds towards the tongue, between 
the stylo-pharyngeus and the stylo-glossus muscles, following the 
course of the last mentioned muscle to the posterior part of the 
tongue. At the commencement of its course it receives a twig 
from the Portio Dura, and one also from the Par Vagum. It 
soon gives off a branch which passes down on the inside of the 
common carotid to the lower part of the neck, where it joins 
some twigs of the intercostal to form the cardiac nerves. After- 
wards it sends off several twigs to the muscles of the pharynx 
and its internal membrane, and also some twigs which unite 
with others from the upper cervical ganglion of the Sympathetic, 
and form a network that lies over the anterior branches of the 
external carotid. The Glosso-Pharyngeal finally enters the 
tongue, at the termination of the hyo-glossus muscle; and after 
sending branches to the lingualis, and the various muscles in- 
serted into the tongue, terminates in small ramifications that are 
spent upon the sides and middle of the root of the tongue, and 
upon the large papillae. 

The Par Vagum 

Are slightly enlarged after passing through the foramen lace- 
rum. As they descend, they adhere to the superior ganglion of 
the intercostal, and also to the ninth pair. They proceed behind 
and on the outside of the carotid, and are contained in the same 
sheath of cellular membrane which encloses that artery and the 

.39* 



462 PAR vagum. 

internal jugular vein. Each of these nerves, soon after it leaves 
the cranium, gives a twig to the glossopharyngeal; soon after 
that it sends off a branch called the Pharyngeal, which unites 
to one from the accessory nerve, and to one or more from the 
glossopharyngeal, and proceeds to the middle constrictor of 
the pharynx, when it expands into ramifications that form a 
plexus from which proceed a number of small twigs that go to 
the larynx, and some that pass down on the common carotid 
artery. 

It then sends off, downward and forward, the Superior Laryn- 
geal nerve, which continues in that direction behind the carotid 
artery, and divides into an external and internal branch. 

The Internal Branch, which is the largest, proceeds between 
the os hyoides and the thyroid cartilage; and divides into nu- 
merous ramifications which are distributed to the arytenoid 
muscles and to the membrane which lines the larynx and covers 
the epiglottis. It is said that fine twigs can be traced into the 
foramina, which are to be seen in the cartilage of the epiglottis; — 
some ramifications can be traced to the pharynx; — others com- 
municate with the branches of the recurrent nerve. 

The External Branch sends twigs to the pharynx, to the lower 
and inner part of the larynx, and to the thyroid gland. 

In its course downwards, the great nerve sometimes sends off 
a twig, which unites with one from the ninth pair that passes to 
the sterno-hyoidei and sterno-thyroidei muscles. 

It uniformly sends off one or more twigs, which pass into the 
thorax and combine with small branches from the sympathetic 
or intercostal nerve, to form the Cardiac plexus, which sends 
nerves to the heart. 

After entering the thorax, the right trunk of the Par Vagum 
passes before the subclavian artery; and the left trunk before 
the arch of the aorta ; and immediately after passing these arte- 
ries, each of the nerves divides into an anterior and posterior 
branch. The anterior is the continuation of the Par Vagum; 
the posterior is a nerve of the Larynx; which from its retro- 
grade course, is called the Recurrent Nerve. 

On the left side the Recurrent Nerve winds backwards round 



PAR VAGUM. 463 

the aorta, and, on the right side, round the subclavian artery, 
and proceeds upwards, deeply seated, on the side of the trachea, 
to the Larynx. Soon after its origin it sends filaments to a 
ganglion of the sympathetic, to the cardiac plexus, and to a pul- 
monary plexus, soon to be mentioned. In its course upwards, 
it sends twigs to the trachea and the oesophagus. It proceeds 
behind the thyroid gland, and sends twigs to that organ. At the 
lower part of the larynx it sends off a branch which communi- 
cates with branches of the superior laryngeal nerve. It also di- 
vides into branches which are spread upon the posterior crico- 
arytenoid, and the arytenoid muscles; and also upon the lateral 
crico-arytenoid and the thyreo-arytenoid muscles, as well as 
upon the membrane which lines the back part of the larynx and 
the contiguous surface of the pharynx. 

There is a difference in the arrangement of the recurrents on 
the different sides, in consequence of one winding round the 
aorta, while the other winds round the subclavian artery. 

After sending off the recurrents, each trunk of the Par Vagum 
proceeds behind the ramifications of the trachea ; but previously 
detaches some small branches, which are joined by twigs from 
the intercostal and from the recurrent, and form a plexus upon 
the anterior part of the vessels going to the lungs. This Ante- 
rior plexus, after sending off some minute branches to the cardiac 
nerves and the pericardium, transmits its branches with the 
bronchia and the blood-vessels, into the substance of the lungs. 

Some of the branches which proceed from the par vagum, 
pass down on the posterior part of the trachea, and enter into 
the membrane which forms it, and the mucous glands which are 
upon it; and some pass to the oesophagus. 

When the par vagum is behind the great vessels of the lungs, 
a number of branches go off transversely, and are also joined 
by some fibres from the sympathetic. These form the Posterior 
pulmonary plexus ; the ramifications from which proceed into 
the substance of the lungs, and are principally spent upon the 
ramifications of the bronchia. It has been said,* that the small 
twigs into which they divide, very generally penetrate into the 

* See Buisson, in the continuation of the Descriptive Anatomy ofBichat. 



464 SPINAL ACCESSORY. 

small ramifications of the bronchia, and are spent upon their in- 
ternal membrane. 

Soon after sending off the nerves of the pulmonary plexus, 
the Par Vagum proceeds downwards upon the oesophagus ; the 
left nerve being situated anteriorly, and the right posteriorly. 
Each of these nerves forms a plexus so as nearly to surround 
the oesophagus, as they descend on it ; but the network is thickest 
on the posterior side. They pass through the diaphragm with 
the oesophagus, and unite again so as to form considerable trunks. 

The Anterior, which is the smallest, proceeds along the lesser 
curvature of the stomach to the pylorus. Some of its fibres are 
spread upon the anterior side of the stomach and the lesser 
omentum. Others of them extend to the left hepatic, and also to 
the solar plexus. 

The Posterior trunk sends branches to surround the cardiac 
orifice of the stomach. Many branches are spread upon the 
under side of the great curvature of the stomach. Some of them 
pass in the course of the coronary artery to the cceliac, and 
unite to the hepatic and splenic plexus ; and one trunk, which is 
thick, although short, proceeds to the solar plexus. 

The Accessory Nerve of Willis, 

Which has been mentioned as associated with the eighth pair 
of nerves, within the cranium, has a very peculiar origin. 

It arises by small filaments, which come off from the spinal 
marrow, between the anterior and posterior fasciculi of the cer- 
vical nerves, and proceeds upwards to the great occipital fora- 
men, between these fasciculi. It commences sometimes at the 
sixth or seventh cervical vertebra, and sometimes about the 
fourth. It enters the cavity of the cranium through the foramen 
magnum, and proceeds upwards and outwards, so as to join the 
eighth pair of nerves at some distance from its origin, and in 
this course it receives filaments from the medulla oblongata. 

After approaching very near to the eighth pair of nerves, it 
accompanies it to the foramen lacerum,and passes out in its own 
separate sheath. It then leaves the eighth pair and descends 
towards the shoulder, proceeding through the sterno-mastoid 



NINTH PAIR OF NERVES. 465 

muscle. Soon after it emerges from the cranium, it sends a 
ramification to the pharyngeal branch of the Par Vagum and 
another to the Par Vagum itself. After passing through the 
upper and back part of the sterno-mastoid muscle it terminates 
in the trapezius. It adheres to the ninth pair of nerves as it 
passes by it, and sends a twig to the sub-occipital and some of 
the cervical nerves. It also gives ramifications to the sterno- 
mastoid muscle as it passes through it. 

It has already been stated that the Laryngeal and Recurrent Nerves appear 
to answer different purposes in their distribution to the Larynx. When 
both of the recurrent nerves are divided in a living animal, the voice 
seems to be lost. When the laryngeal nerves only are divided, the strength 
of the voice remains, but it is flatter. The recurrent nerves, therefore, 
seem essential to the formation of the voice. The laryngeal nerves are 
necessary to its modulation. 

The history of the investigation of this subject is contained in Mr. Haigh- 
ton's paper in the third volume of Memoirs of the Medical Society of 
London. 

The Ninth Pair of Nerves. 

Each of these nerves arises from the groove in the medulla 
oblongata, between the corpora pyramidalia and the corpora 
olivaria. Three or four fasciculi, of distinct filaments, unite to 
form it. Thus composed, it proceeds to the anterior condyloid 
foramen of the occipital bone, and passes through the dura 
mater. It seems firmly united, by the cellular membrane, to 
the eighth pair, and to the first ganglion of the sympathetic, 
soon after it passes from the occipital bone. It is either con- 
nected to the sub-occipital nerve by a small ramification, or it 
joins a branch which proceeds from the sub-occipital to the cer- 
vical, and bends round the transverse process of the atlas. It 
passes between the internal carotid artery and the internal jugular 
vein, and crosses the external carotid at the origin of the occi- 
pital artery. At this place it generally sends downwards a 
large branch which is called the Descendens JVoni. Passing for- 
wards, it is on the outside of the posterior portion of the digastric 
muscle, and inclines downwards; but near the tendon of the 



466 CERVICAL NERVES. 

muscle it turns upwards, and proceeds on the inside of the mylo- 
hyoideus, where it divides into ramifications, which, at the ante- 
rior edge of the hyo-glossus muscle, begin to enter into the sub- 
stance of the tongue, between the genio-glossus and the lingualis 
muscles. 

Some of the branches of this nerve unite with those of the 
lingual branch of the fifth pair. Others are distributed to almost 
all the muscles connected with the tongue. 

The branch called descendens noni passes down in the course 
of the common carotid artery, and sends branches in its progress 
to the upper portions of the coraco-hyoid and sterno-thyroid 
muscles; it unites with ramifications of various sizes from the 
first, second, and third cervical nerves, which form a bow under 
the sterno-mastoid muscle, from which ramifications go to the 
lower portions of the sterno-hyoid and thyroid muscles, and of 
the coraco-h) oid. 

Of the Cervical Nerves. 

The tenth or last pair of the head, commonly called the Sub- 
occipital, may be arranged with these nerves, because they arise, 
like them, from the medulla spinalis, and are distributed to the 
muscles on the neck. 

The Sub-occipital Nerves 

Arise on each side of the spinal marrow, nearly opposite to 
the interval between the great foramen of the os occipitis and 
the atlas. 

Each of these nerves consists of an anterior and posterior fas- 
ciculus, or bundle of fibres, which pass outwards immediately 
under the vertebral arteries, and form a ganglion, from which 
proceed an anterior and a posterior branch. 

The anterior branch is united to the second cervical nerve 
below, and to the ninth nerve, or the hyoglossal, above. It also 
sends filaments to the upper ganglion of the great sympathetic 
nerve. 

The posterior branch is spent upon the Recti, the Obliqui, and 
some other muscles of the head. 



CERVICAL NERVES. 407 

The proper Cervical Nerves consist of seven pairs; of which 
the first six go oft' between the vertebrae of the neck, and the 
seventh between the last of the neck and the first of the back. 

The First Cervical Nerve 

Passes out between the atlas and the Vertebra Dentata. It 
originates from two fasciculi, which are connected to each other 
at a ganglion, and then separate into an anterior and a posterior 
branch.* 

The anterior branch is connected by filaments with the acces- 
sory nerve, with the ninth pair of the head, and with the upper 
ganglion of the sympathetic. It is also connected with the 
second cervical nerve, and sends some branches to the muscles 
on the anterior part of the spine. 

The posterior branch, after communicating with the posterior 
branches of the sub-occipital and the second nerves of the neck, 
perforates the complexus muscle, and ascending upon the back 
of the head, is distributed with the occipital artery. 

The Second Cervical Nerve 
Sends off, from its Anterior Branch, a twig which descends to 
the lower cervical ganglion of the sympathetic, and a consider- 
able ramification to the third cervical nerve. It also sends ofF 
some twigs to the sterno-mastoid muscle, and others to join the 
accessory nerVe. Some of its small ramifications pass down 
upon the external jugular vein, and others unite with the descend- 
ing branch of the ninth pair of the head. A small branch is also 
concerned in the formation of the phrenic nerve. Two larger 
branches of this nerve wind round the posterior edge of the 
sterno-mastoid, and are spread under the integuments of the an- 
terior, lateral, and posterior parts of the neck and lower parts of 
the head ; they have a communication with the portio dura of 
the seventh pair.f The posterior branch of this nerve is spent 
upon the extensor muscles of the head and neck. 

* This arrangement is common to the nerves of the spine. The ganglion is 
formed by the posterior fasciculus. 

t These superficial branches have sometimes been described as coming from a 
plexus; but they often arise directly from the second cervical nerve. 



468 CERVICAL NERVES. 

The Third Cervical Nerve 

Sends down, from its interior Branch, the principal trunk of 
the phrenic nerve. It also sends twigs to the fourth cervical, to 
the lower cervical ganglion of the intercostal, and to the descend- 
ing branch of the ninth of the head. Some of its branches unite 
with twigs of the accessory nerve, and others are spent upon the 
muscles and integuments of the shoulder and lower part of the 
neck. A small Posterior Branch is spent upon the muscles of 
the back of the neck. 

The Nerves of the Diaphragm 

Are generally denominated the Phrenic. The principal root 
of each of them is commonly derived from the third cervical 
nerve, but frequently the second and the fourth cervical nerves 
contribute to the formation ; and they are sometimes joined by 
a twig which is derived from the ninth pair. 

Each nerve proceeds down the neck, between the rectus capi- 
tis major and the scalenus anticus, and continues along the fore 
part of the scalenus anticus ; it descends into the thorax within 
the anterior end of the first rib, between the subclavian vein and 
the artery. It sometimes receives a twig from the fifth cervical 
nerve, and a twig passes between it and the great sympathetic. 
After entering the thorax, they descend, attached to the medias- 
tinum, before the root of the lungs. In consequence of the pro- 
jection of the point of the heart to the left, the course of the left 
is a little different from that of the right; that of the right pro- 
ceeding in a more perpendicular direction. When they arrive 
at the diaphragm, they divide into many ramifications, which 
have a radiated arrangement, and terminate on the fibres of that 
muscle, both on the upper and lower surface. Some fibres from 
each nerve are continued downward, and communicate in the 
abdomen with fibres from the intercostal. 

The Fourth, Fifth, Sixth, and Seventh Cervical Nerves 
May be comprised in one description. They pass off succes- 
sively from the medulla spinalis, between the vertebras, like the 



BRACHIAL PLEXUS. 4^9 

other nerves. Their Posterior Branches are generally distributed 
to the back of the neck, and are very small. Their Anterior 
Branches are principally appropriated to the upper extremities, 
and are large. They generally send each a small twig to the 
lower cervical ganglion of the intercostal nerve, and a few small 
branches to some of the contiguous muscles. They are arranged 
and combined so as to form the net-work, now to be described, 
which is called the Brachial or Axillary plexus; and, in the 
formation of this plexus, they are joined by the first dorsal nerve. 

The Brachial Plexus 

Extends from the lower part of the side of the neck into the 
arm-pit. It commences in the following manner. The fourth 
and fifth cervical nerves proceed downwards, and after uniting 
to each other about an inch and a half below their egress from 
the spine, they separate again, almost immediately, into two 
branches. 

The sixth cervical nerve, after passing downwards, divides 
also into two branches, one of which unites with the uppermost 
branch that proceeds from the union of the fourth and fifth, and 
the other with the lowermost, and they all proceed downwards. 

The seventh cervical is joined by the first dorsal, which pro- 
ceeds upwards, and unites with it at a short distance from the 
spine. The cord produced by their junction soon unites with 
one of the cords above described. As these different cords pro- 
ceed downwards, they divide, and their branches again unite. 
The axillary artery, which passes in the same direction, is sur- 
rounded by them. In this manner the axillary plexus is often 
formed. 

The muscles about the shoulder, both before and behind, are 
supplied by the axillary plexus. Thus, it sends branches to the 
Sub-scapularis, Teres Major, and Latissimus Dorsi, behind; and 
to the Pectoralis Major and Minor, and the Mamma, before. It 
also sends off a branch called the Scapularis, which commonly 
arises from the upper part of the plexus, and proceeds through 
the notch in the upper costa of the scapula to the supra and infra 
spinatus, teres minor, &c. 

vol. it. 40 



470 NERVES OF THE ARM. 

Nerves of the Arm. 

All the great nerves of the arm are derived from the axillary 
plexus. There are six of them, which are denominated The 
Musculo-Cutaneus ; The Median;* The Cubital, or Ulnar; The 
Internal Cutaneus; The Radial or Muscular Spiral; and the 
Circumflex or Articular. 

The Musculo-Cutaneus, or Perforating Nerve, passes obliquely 
through the upper part of the coraco-brachialis muscle. Before 
it enters the muscle, it sends a branch to it. After leaving the 
muscle it passes down the arm between the biceps and the bra- 
chialis internus, to which it also gives branches. It proceeds to 
the outside of the biceps, and continues under the median cepha- 
lic vein to the anterior and external part of the fore-arm; along 
which it passes under the integuments. On the lower part of 
the fore-arm it divides into many branches, which extend to the 
root of the thumb and the back of the hand, and terminate in the 
integuments. 

The Median Nerve, which is one of the largest of the arm, 
often proceeds from the axillary plexus next to the musculo-cu- 
taneus; it passes down the arm, very near the humeral artery, 
within the edge of the biceps flexor muscle, and, during this 
course, gives off no branches of any importance. After passing 
the bend of the elbow, it proceeds under the aponeurosis of the 
biceps, between the brachialis internus and the pronator teres, 
and continues down near the middle of the fore-arm, between 
the flexor sublimis and the flexor profundis. At the elbow it 
sends branches to several muscles on the anterior side of the 
fore-arm, and to the integuments. Among these branches is 
one, called the Interosseal Nerve, which passes down on the an- 
terior surface of the interosseal ligament, with the artery of that 
name. This nerve sends branches, in its course, to the long 
flexor of the thumb, and the deep flexor of the fingers. When 
it arrives at the pronator quadratus, it sends branches to that 
muscle, and, passing between it and the interosseus ligament, 

* Sometimes called Brachial. 



NERVES OF THE ARM. 471 

perforates the ligament, and soon terminates on the posterior 
side of the wrist and hand. 

As the Median Nerve proceeds downwards, it becomes more 
superficial; and continuing among the tendons of the flexors of 
the fingers, it gives off a branch which is principally spent upon 
the integuments of the palm of the hand. This great nerve 
passes with the tendons under the annular ligament; and imme- 
diately after, while it is covered by the Aponeurosis Palmaris, 
and by that portion of the artery which is called Arcus Subli- 
mits, it divides into branches, which separate from each other at 
acute angles, and subdivide so as to send a ramification to each 
side of the thumb, of the index, and of the middle finger; and to 
the radial side of the ring finger. 

The Cubital or Ulnar Nerve is also of considerable size. It 
passes down on the inside of the triceps extensor muscle, to the 
great groove formed by the olecranon process and the internal 
condyle of the os humeri ; and, in this course, it often sends a 
branch to the triceps, and some smaller twigs to the upper part 
of the fore-arm. From the groove it proceeds on the anterior 
part of the fore-arm, between the flexor carpi ulnaris and the 
flexor sublimis, to the wrist. At a small distance above the wrist 
it sends off a branch, called the Dorsalis, which passes between 
the flexor ulnaris and the ulna, to the back of the fore-arm and 
wrist, where, after sending ramifications to the integuments and 
contiguous parts, it divides into branches which pass to the little 
finger and the finger next to it. Those branches send off, in 
their course, many twigs which pass to the skin and cellular sub- 
stance. 

The ulnar nerve then proceeds with the artery, over the annu- 
lar ligament, on the radial side of the os pisiforme, and divides 
into two branches; one of which is superficial, and the other 
deep-seated. 

The Superficial divides into two principal branches, an exter- 
nal and an internal. The external passes under the aponeurosis 
palmaris; and, after sending a branch to combine with one from 
the median and some twigs to the contiguous muscles, it subdi- 
vides into two branches, one of which goes to the ulnar side of 



472 NERVES OF THE ARM. 

the ring finger and the opposite side of the little finger. The 
other branch sends off some twigs to the muscles, and proceeds 
along the ulnar side of the little finger. 

The Deep-sealed palmar branch of the ulnar nerve passes be- 
tween the muscles of the little finger, under the tendons of the 
flexors, and accompanies the deep-seated arterial arch in the 
palm of the hand, giving branches to the interossei, and other 
contiguous muscles. 

The Radial or Muscular Spiral nerve is one of the largest 
nerves of the arm. It passes from the axillary plexus down- 
ward, backward, and outward, under the triceps muscle to the 
external side of the os humeri. In this course, it gives off se- 
veral branches to the different portions of the triceps. It also 
frequently gives off a large branch, which passes downwards on 
the outside of the olecranon, to the back of the fore-arm, and 
continues to the back of the hand, furnishing many branches 
which terminate in the integuments. It then proceeds down- 
wards between the supinator radii longus and the brachialis in- 
ternus. Immediately after passing the articulation of the elbow, 
it divides into two branches, denominated the Superficial and the 
Profound. The Superficial soon joins the radial artery, and 
proceeds downwards, sending branches to the contiguous mus- 
cles. In its course about the middle of the arm it crosses the 
tendon of the supinator longus, and proceeds between it and the 
tendon of the extensor carpi radialis longior; it soon after di- 
vides into two branches, which are principally distributed to the 
thumb and fore-finger, and also to the integuments. 

The Profound branch proceeds to the back of the fore-arm 
under the radial extensor, and continues to the back of the wrist 
and hand. In this course it divides into two branches, which 
are distributed to the contiguous muscles and tendons, and the 
integuments. 

The Internal Cutaneus nerve is the smallest of the nerves 
which proceed from the axillary plexus. It descends in the 
course of the basilic vein, and very near it. Above the elbow it 
divides into an Internal branch, which proceeds over the Basilic 
Fein, and separates into branches that pass down on the side of 
the fore-arm ; and an External Branch that passes under the 



DORSAL NERVES. 473 

Median Basilic Vein, and continues down on the anterior part of 
the fore-arm. 

The Articular or Circumflex nerve proceeds backwards from 
the plexus, between the teres major and minor, and passes nearly 
around the body of the os humeri, at a small distance below its 
head. It is distributed to the contiguous muscles and to the arti- 
culation ; but its principal branches terminate in the deltoid 
muscle. 

The Dorsal Nerves 

Proceed from the cavity of the spine between the dorsal ver- 
tebrae. They are sometimes called Intercostals, because they 
pass between the ribs, like the blood-vessels of that name. 
There are twelve pairs of them, and they are named numerically, 
beginning from above. 

These nerves proceed from the medulla spinalis by two fasci- 
culi of fibres — one from each of its lateral portions — the poste- 
rior fasciculus is the largest. After passing through the lateral 
foramen and the dura mater, a ganglion is formed by the poste- 
rior fasciculus: the anterior fasciculus unites to this ganglion at 
its external extremity ; and one nerve is formed, which almost 
immediately divides into an anterior and a posterior branch, of 
which the anterior is the largest. 

The posterior branch proceeds backwards, and is distributed 
to the muscles of the back. The anterior branch passes towards 
the angle of the rib, in contact with the pleura. Soon after its 
origin, this anterior branch sends off two ramifications which 
unite to the intercostal nerve, at the ganglion ; it then proceeds 
forwards with the blood-vessels, between the internal and exter- 
nal intercostal muscles, in the groove near the lower margin of 
the ribs; and terminates on the anterior part of the thorax. In 
its course it sends branches, not only to the intercostal muscles 
and pleura, but to the other muscles and the integments of the 
thorax. 

Some of the dorsal nerves differ from the others, as to the 
ramifications which they send off. 

The first nerve, of this order, joins the lower cervical nerves 

40* 



474 LUMBAR NERVES. 

in the axillary plexus; but it sends off the ramifications to the 
sympathetic, and also a branch, which passes under the first rib, 
like the other dorsal nerves. 

The second nerve sends off a branch, which passes through 
the external intercostal muscle into the axilla, and combines 
there with a branch of the cutaneous nerve, being distributed to 
the internal and posterior part of the arm. 

The third dorsal nerve also sends off a branch, which is 
distributed to the axilla and the back part of the arm. 

These branches of the second and third dorsal nerves, are 
called intercosto-humeral nerves. 

The lower dorsal nerves supply the muscles and integuments 
of the abdomen. 

Of the Lumbar Nerves. 

There are five pairs of these nerves. The first of them passes 
off between the first and second of the lumbar vertebrae, and the 
others succeed regularly ; so that the last pair is situated between 
the last lumbar vertebra and the sacrum. 

The first lumbar nerves arise from the medulla spinalis, before 
it forms the cauda equina ; the other four pair are formed by the 
cauda equina. 

They commence by anterior and posterior fasciculi, which 
are united at a ganglion. From this ganglion, anterior and 
posterior branches go off, which are very different in size, the 
anterior being the largest. 

The posterior branches are distributed to the muscles of the 
back. The anterior send branches to the ganglions of the sym- 
pathetic nerve, and also communicate with each other to form 
the Lumbar Plexus, which is situated on the lateral parts of the 
bodies of the lumbar vertebras, before their transverse pro- 
cesses, and supplies nerves to the muscles of the thigh. 

The First Lumbar Nerve 

Is connected, by its anterior branch, to the last dorsal and the 
second lumbar. From the same branch ramifications go off to 
the Quadratus Lumborum, and obliquely across that muscle, to 



LUMBAR NERVES 475 

the lower part of the abdominal muscles near the spine of the 

ilium. 

TJie Second Lumbar Nerve 

Sends off a muscular branch downwards and outwards : it 
also sends off the small branch, called the External Spermatic, 
which passes down in such a direction, that it perforates the 
transversalis and the obliquus internus muscles, near their lower 
margin, at a small distance from the superior anterior spine of 
the ilium, and then proceeds within the lower edge of the tendon 
of the external oblique to the abdominal ring, through which it 
passes. In the male it is distributed to the spermatic cord and 
scrotum, and in the female to the labia pudendi. In the female 
it also sends a branch to the uterus.* The Second Lumbar, after 
sending off these branches, passes downwards, and joins the 
Third lumbar nerve. From this union of the second and third 
nerves, a branch called the Cutaneus Medius, which will be soon 
described, proceeds downwards. 

After sending off this branch, the united trunk of the second 
and third joins the Fourth; and from this union is sent off the 
Obturator Nerve, which passes through the aperture in the mem- 
brane that closes the foramen thyroideum; the Crural Nerve, 
which passes under Poupart's ligament ; and a third branch that 
proceeds downwards, and joins the Fifth lumbar nerve. The 
Fifth lumbar nerve, with this accession from above, descends 
into the pelvis, and unites with the sacral nerves. 

This arrangement of the lumbar nerves constitutes the Lumbar 
Plexus, which, as has been already stated, furnishes three nerves 
to the lower extremity, namely, the Cutaneus Medius, the Ob- 
turator, and the Crural Nerve. 

The Cutaneus Medius, which arises from the union of the 
second and third nerves, as has been already observed, proceeds 
downwards, and frequently adheres to the crural nerve, for a 
short distance, near Poupart's ligament, but soon leaves it, and 
descends on the inside of the thigh, supplying the integuments as 
low as the knee. 

* The external spermatic often comes off from the first lumbar nerve. 



476 ANTERIOR CRURAL NERVE. 

The Obturator Nerve 

Descends into the pelvis, and passes out of it at the upper 
part of the foramen thyroideum ; proceeding downwards in an 
internal direction, to be distributed on the inside of the thigh. 

This nerve is generally accompanied by the obturator artery 
and vein : the artery being above, and the vein below it. When 
it has arrived at the foramen ovale or thyroideum, it sends off a 
branch to the internal and external obturator muscles, and, after 
passing these muscles, divides into two branches, which are 
distributed to the muscles on the inside of the thighs, the adduc- 
tors, the pectineus, the gracilis, &c. 

The Crural Nerve 

Is situated at first behind, and then on the outside of the psoas 
muscle. It passes under Poupart's ligament with the great fe- 
moral vessels, being on the outside of the artery. 

It is distributed to the integuments, and also to the muscles, 
which are situated on the anterior and internal parts of the thigh. 
Some of its ramifications go off before it passes under Poupart's 
ligament. Several of them are spent upon the integuments, and 
are, therefore, denominated Cutaneus. — They are distinguished 
by the terms Cutaneus Anterior, Cutaneus lnternus, &cc, ac- 
cording to their situations. 

The deep-seated branches are the largest. They are principally 
spent upon the muscles on the anterior and the internal side of 
the thigh, namely, the four extensors, the adductors, the pectineus, 
the sartorius and the gracilis. Among these nerves there is one, 
called the Saphenus, which has a different destination. It ac- 
companies the great artery of the thigh to the place where it 
perforates the Adductors; it there separates from the artery, and 
passes over the tendon of the Adductors, under the sartorius 
muscle; thence it continues, with the great saphena vein on the 
inside of the leg, to the internal ankle; sending branches to the 
integument, in its course. It terminates in skin and cellular 
substance on the upper and internal surface of the foot. 



SACRAL NERVES. 477 

The Sacral Nerves 

Are composed of those cords of the cauda equina which 
remain after the formation of the lumbar nerves. They are 
frequently stated to consist of five or six pairs, four of which 
pass through the foramina of the sacrum, and the fifth between 
the sacrum and the os coccygis.* The cords of which they are 
respectively composed arise by anterior and posterior fasciculi. 
When they have arrived opposite to the foramina of the sacrum, 
through which they are to pass, a ganglion is formed, at which 
they unite, and then divide into anterior and posterior branches.f 
The uppermost of the anterior branches are large, and pass 
through the anterior foramina of the sacrum. The posterior are 
small, and go through the posterior foramina. 

The Posterior branches are generally spent upon the muscles 
which lie on the sacrum and posterior parts of the pelvis, ex- 
ternally. 

The anterior branches of the three first nerves send ramifica- 
tions to the sympathetic. They unite to each other, and are 
joined by the last lumbar nerve, and by a branch of the fourth 
sacral, in the formation of the great sciatic nerve. This union 
constitutes the Sciatic plexus. 

The anterior branch of the fourth nerve transmits branches to 
the sympathetic : it also sometimes sends a branch to the united 
nerves above, or the sciatic plexus. It sends branches to the 
hypogastric plexus, and to the contiguous muscles. 

The fifth and sixth pairs, which are very small, terminate also 
in the contiguous muscles and in the integuments. 

From the Sciatic plexus, or the nerves which compose it, 
several smaller branches go off. There are generally two which 
pass off backwards through the ischiatic notch, and are denomi- 
nated Gluteal, as they are distributed to the glutei muscles. 
From the lowermost of these a branch descends on the thigh. 

The Pudic nerve, which is appropriated to the organs of ge- 

* The sixth pair, when they exist, proceed in a groove in the os coccygis. 
t The ganglions of the fourth and fifth nerves are extremely small, and not so 
near the foramina as those of the others. 



478 SCIATIC NERVE. 

neration, also passes off from this plexus, and appears to consist 
of fibres which are derived from each of the nerves that com- 
pose it. It proceeds between the sacro-ischiatic ligaments and 
divides into two branches — an inferior and a superior. The 
inferior passes between the erector penis and the accelerator 
urinae muscles, and is distributed to those muscles, to the bulb of 
the urethra and the interior of that canal, to the scrotum and 
dartos. 

The superior proceeds along the os pubis to the symphysis, 
and passes between the bone and the body of the penis to the 
dorsum. A considerable branch accompanies the artery on the 
dorsum, and terminates by many ramifications, on the glans 
penis ; after sending branches in its course to the integuments 
generally, and to the prepuce. 

In females, the Inferior pudic nerve proceeds along the ex- 
ternal labia pudendi to the mons veneris, sending off many 
ramifications in its course. 

The Superior pudic nerve proceeds as in males, along the 
branch of the pubis to the superior surface of the clitoris, and 
terminates principally upon the extremity of that organ. 

The sacral nerves unite in the sciatic plexus to form the great 
nerve of the lower extremity, which is next to be described. 

The Great Sciatic Nerve 

Proceeds from the pelvis through the ischiatic notch, between 
the pyramidalis, and the superior gemellus muscle; it then passes 
down to the back part of the thigh, between the tuberosity of 
the ischium and the great trochanter of the os femoris; and 
continues downwards, inclining from within outwards, to the 
ham, where it is situated between the tendons of the semi-tendi- 
nosus and semi-membranosus on the internal side, and the tendon 
of the biceps on the external. In this course it sends off branches 
to the muscles on the posterior part of the thigh. 

As the great nerve passes down the thigh, it sends off" obliquely 
downwards and outwards, a large branch which is called the 
Fibular, that passes across the head of the fibula to the external 
and anterior part of the leg. The place where this branch 



PERONEAL NERVE. 479 

separates from the main nerve is different in different subjects' 
It continues in contact with it for some distance, connected only 
by cellular membrane. 

The Fibular or Peroneal Nerve 

Proceeds downwards on the inside of the tendon of the biceps, 
and crosses obliquely to the outside of the external head of 
the gastrocnemius : it then passes inwards between the pero- 
neus longus muscle and the fibula : and descending between the 
muscles on the front of the leg, divides into two branches, one 
of which inclines to the exterior side of the leg, and the other 
preserves an internal situation. Jn its course from the great 
sciatic nerve to the fibula, it sends off some superficial ramifica- 
tions. The two branches into which it divides, after passing 
over the fibula, continue downwards. The Internal, after sup- 
plying the muscles on the anterior part of the leg, passes under 
the annular ligament like the anterior tibial artery; and on the 
upper part of the fool, divides into two ramifications, one of 
which proceeds forwards near the internal edge of the foot and 
the other near the external ; they divide again, and are distributed 
to the parts on the upper surface of the foot, one of their ranula 
descending with the continuation of the anterior tibial artery to 
the sole of the foot. 

The External Branch of the fibular nerve, as it proceeds 
downwards, supplies ramifications to the contiguous muscles, 
and passing through the fascia on the outside of the leg, con- 
tinues between it and the skin towards the foot. In this course 
it generally divides into two branches, which are spent upon the 
upper surface of the foot. 

The Great Sciatic Nerve, after the fibular nerve leaves it, 
continues down the thigh, between the tendons of the flexors, 
behind the great blood-vessels, and, of course, exterior to them. 

In the ham, this great nerve takes the name of Popliteal, and 
proceeds across the articulation of the knee, between the heads 
of the gastrocnemii, to the posterior side of the tibia : here it 
passes through the upper portion of the soleus or gastrocnemius 
internus, and continues between it and the long flexor of the toes, 



480 DISTRIBUTION OF THE TIBIAL NERVE. 

near the Posterior Tibial Artery; descending with that artery to 
the hollow of the os calcis. In this situation it has the name of 

Posterior Tibial Nerve. 

At the commencement of this course, a small distance below 
the internal condyle of the os femoris, it sends off a branch of 
considerable size, called the Communicans Tibia, or Saphena 
Externa, which passes down behind the gastrocnemii, and gra- 
dually inclines externally, so that it is situated on the external edge 
of the tendo Achillis, soon after the commencement of that 
tendon, and proceeds behind the external ankle, near the outer 
side of the foot, to the smaller toes: distributing branches to the 
contiguous parts. Jn its course on the back of the leg, it sends 
off a branch which unites with one of the superficial ramifica- 
tions of the fibular nerve, and descends to the outer part of the 
foot. 

The Tibial Nerve, in its course downwards, sends branches to 
the contiguous muscles, and a few twigs which form a species of 
network on the artery. In the hollow of the os calcis it sends 
off a superficial branch to the integuments of the sole of the 
foot, which proceeds on the outside of the aponeurosis plantaris: 
it there also divides into branches, which are denominated the 
Internal and External Plantar Nerves. 

The Internal Plantar Nerve proceeds forwards, alongside of 
the tendon of the long flexor muscle of the great toe, giving off 
small branches in its course; about the middle of the^foot it 
divides into four branches, one of which proceeds to the inside 
of the great toe ; and a second to the angle formed by the great 
toe and the toe next to it, where it divides and sends a branch to 
the opposite sides of those toes: the other two branches are dis- 
tributed in a similar manner, to the succeeding toes. These 
digital branches are connected with each other by small ramifi- 
cations. 

The External Plantar Nerve proceeds with the external plantar 
artery towards the external side of the foot, between the short 
flexor of the toes and the flexor accessorius. Near the external 
edge of the foot, about the posterior end of the metacarpal bones, 



COMMENCEMENT OP THE SYMPATHETIC NERVE. 4gJ 

it divides into three branches. One proceeds to the outside of 
the little toe ; another passes to the angle between the fourth toe 
and the little toe, and divides into branches which are distributed 
to the corresponding sides of these toes. The third branch pro- 
ceeds more deeply in the foot, from the external towards the 
internal edge of it, and is spent upon the deep-seated contiguous 
muscles. 

The Great Sympathetic or Intercostal Nerve 

Commences in the cranium with those small ramifications of 
the pterygoid branch of the upper maxillary nerve, and of the 
sixth pair, which accompany the carotid artery through the canal 
in the petrous portion of the temporal bone. These small nerves 
form a network which surrounds the artery in the canal and 
gives rise to the incipient sympathetic, a small cord which passes 
down close to the nerves of the eighth and ninth pairs of the 
neck. Opposite to the second cervical vertebra, this nerve is 
swelled or dilated, so as to form a body of a light red colour, 
which is more than an inch in length, and has the form of two 
cones united to each other at their bases. This is the Superior 
Cervical Ganglion of the Sympathetic Nerve, and from it the 
nerve descends, behind the Par Vagum, on the front part of the 
neck. 

This ganglion receives twigs from the first, second, third, and 
fourth pairs of cervical nerves, and also from the eighth and ninth 
nerves of the head. It sends off several twigs, which pass be- 
hind the carotid artery, at its bifurcation, and are joined by twigs 
of the Portio Dura and the Glossopharyngeal nerves. From 
these united twigs proceed very small ramifications, which ac- 
company several branches of the external carotid artery, and 
some of them pass down with the Common Carotid. 

This superior ganglion also furnishes small twigs which ac- 
company the Glosso-Pharyngeal to the tongue and pharynx. 
Sometimes a twig from it passes on the back part of the thyroid 
gland to commnnicate with the recurrent nerve. From this gan- 
glion go off some small branches, which, uniting with others 

VOL. II. 41 



482 SYMPATHETIC NERVE.-CERVICAL GANGLIA. 

from the superior laryngeal nerves, form the superior or super- 
ficial cardiac nerve, which will be soon described. 

The trunk of the Sympathetic Nerve descends, on the front of 
the neck, from this ganglion, as has been already stated. In its 
course it receives very small twigs from the fourth and fifth cer- 
vical nerves, and sends some very small twigs which appear to 
go to the oesophagus, and some which unite to the laryngeal 
nerve and go to the thyroid gland. Some twigs which are larger 
proceed from it into the thorax, and go to the cardiac plexus 
hereafter to be described. 

Opposite to the interval between the fifth and sixth cervical 
vertebras it forms another ganglion, of an irregular shape, much 
„ smaller than the first. This ganglion, in different subjects, differs 
in size as well as in several other respects. Sometimes it is en- 
tirely wanting, and sometimes it is doubled. It is denominated 
the Middle Cervical, or Thyroid Ganglion. When the fourth, 
fifth, and sixth cervical nerves do not send ramifications to the 
sympathetic nerve, this ganglion receives twigs from them. 

The Middle Cervical, or Thyroid Ganglion sends many rami- 
fications downwards. Some of them enter the thorax and con- 
tribute to the formation of the Cardiac Plexus; others accom- 
pany the inferior thyroid artery, and, with twigs from the 
recurrent nerve, form a plexus which extends towards the thy- 
roid gland. Some proceed downwards before, and others be- 
hind, the subclavian artery, to the next ganglion ; among them 
is generally one which may be regarded as the trunk of the 
Sympathetic. 

This third Ganglion is denominated the Inferior Cervical, or 
the First Thoracic. It is almost constantly found in the same 
situation, viz. between the transverse process of the last cervical 
vertebra and the head of the first rib, and is partly covered by 
the origin of the vertebral artery. It is generally larger than 
the middle ganglion. It receives branches from the sixth and 
seventh cervical, and the two first dorsal nerves. Ramifications 
pass from it to the par vagum and recurrent nerve, and also to 
the cardiac and pulmonary plexus. 



CARDIAC NERVES.-CARDIAC PLEXUS. 483 

From this ganglion the Sympathetic Nerve proceeds down- 
wards on the side of the spine, as will be described hereafter. 

The Nerves of the Heart, 
Being derived from branches which have already been men- 
tioned, are now to be described. 

They arise principally from an arrangement of nerves deno- 
minated the Cardiac Plexus, or Plexuses, which is situated above 
the curve of the aorta, and extends, on the posterior side of it, 
from the root of the arteria innominata to the bifurcation of the 
pulmonary artery. This plexus is composed of nerves which are 
principally formed by the union of small ramifications that are 
derived from the three above mentioned ganglions of \he Sympa- 
thetic Nerve, and the nerve itself; and also from the Par Vagum, 
and some of its branches. 

These nerves are denominated the Cardiac. They descend 
on their respective sides of the neck, but are somewhat different 
on the different sides. On the right side three nerves have been 
described as particularly entitled to this name, and on the left 
side but two. 

The first on the right side is denominated Superior, or Super- 
ficial Cardiac Nerve. It generally arises by several fine threads, 
which unite into one delicate cord that passes down by the side 
of the common carotid. When it has arrived on a line with the 
middle ganglion, it sends a twig to the thyroid plexus, and 
another that communicates with a twig from the par vagum, 
which continues downwards on the carotid artery. After pass- 
ing beyond the ganglion, it divides into several branches, which 
unite themselves to branches of the recurrent nerve that are 
going to the middle ganglion. 

The second, which is denominated the Middle Cardiac, the 
Great Cardiac, or the Deep Cardiac, is the largest of the three. 
It arises from the Middle Cervical, or Thyroid Ganglion, by five 
or six fine fibrils, which finally form one, that passes before and 
across the subclavian : and at that place, as well as lower down, 
it receives twigs from the par vagum : below this, it is joined by 



4Q4 CARDIAC NERVES. 

a considerable twig from the recurrent, and terminates in the 
Cardiac Plexus, to which it contributes largely. 

The third cardiac nerve of the right side is called the Inferior, 
or the Small Cardiac Nerve. It originates from the third, or 
lower cervical ganglion, by many fibrils which unite into a 
smaller number that form a plexus. It crosses behind the sub- 
clavian, and proceeds on the outside of the arteria innominata 
to the curve of the aorta ; continuing between it and the pul- 
monary artery, to the anterior coronary plexus. In this course 
it receives several fibres from the recurrent and the par vagum. 

On the left side the first cardiac nerve arises from the upper 
ganglion. The second derives its origin from the two lower 
ganglions. 

The left superior or superficial cardiac nerve arises like the 
right, by many distinct fibres, and proceeds downwards in the 
same way. It descends between the carotid and the subclavian, 
and when it has arrived at the place where they originate from 
the aorta, it divides into a great number of small ramifications. 
Some pass before the aorta, either to join the branches of the 
inferior cardiac, or to unite with the cardiac branches of the left 
nerve of the par vagum. The others proceed behind the aorta, 
and enter into the common cardiac plexus. 

The second cardiac nerve of the left side may be called the 
Great Left Cardiac, and has a double origin, as above men- 
tioned. The principal branch in its composition arises from the 
lowest cervical ganglion, and passes behind the transverse por- 
tion of the subclavian artery. Where the inferior thyroid artery 
arises from the subclavian, this branch receives a considerable 
number of ramifications, which arise from the upper ganglion, and 
are interwoven with each other before they unite to it. It passes 
behind the curve of the aorta, and terminates in the great cardiac 
plexus, which it particularly contributes to form. Here it is 
joined by many fibres from the par vagum. 

The Cardiac Plexus 
Is situated principally behind the curve of the aorta, at a 



CARDIAC PLEXUS 485 

small distance above the heart. It commences as high as the 
origin of the arteria innominata, and extends downwards to the 
bifurcation of the pulmonary artery. 

As has been already mentioned, it is principally composed of 
branches from the middle cardiac nerve of the right side, and 
the inferior cardiac nerve of the left; but it receives branches 
from the superior cardiac of the left, and sometimes of the right 
side. Some fibres of the inferior cardiac of the right are also 
united to it. 

Many branches proceed from this plexus. 

A small number pass upon the aorta, and seem to enter into 
its texture.* 

Some of them also combine with the ramifications of the Par 
Vagum in the anterior pulmonary plexus. 

The majority proceed to the basis of the heart, near the origin 
of the pulmonary artery and the aorta, and constitute the proper 
nerves of that organ. They accompany the coronary arteries, 
and are so arranged around them that, by some anatomists, they 
have been said to form plexuses, which have been denominated 
Coronary. 

The Sijmpathetic Nerve, as has been stated above, proceeds 
from the ganglion, called the Lower Cervical, or the First Tho- 
racic, before the neck of the first rib. It continues to descend, 
in the same direction, along the spine, exterior to the pleura, to 
the inferior part of the thorax. Near the head of each rib it 
forms a ganglion, which unites with the intercostal nerve behind 
it, by two branches, and thus forms an indirect communication 
with the medulla spinalis. 

From several of the uppermost of these ganglions small twigs 
proceed to the pulmonary plexus, and also to the great trunk of 
the aorta, below the curve forming a species of network, or 
plexus upon it. 

From the ganglions near the heads of the fifth and sixth ribs, 
and from four or five of the ganglions which succeed them, 
small nerves arise, which proceed downwards on the sides of 

* It has been asserted that some of the anatomists of Paris have traced these 
nerves on the aorta, to a great distance from the heart. 

41 * 



486 SPLANCHNIC NERVES.-SEMILUNAR GANGLI0N.-S0LAR PLEXUS. 

the bodies of the vertebrae, and unite into one trunk that is de- 
nominated the Splanchnic Nerve, because it is distributed to the 
viscera of the abdomen. — This nerve proceeds behind the crus 
of the diaphragm, on its respective side, into the abdomen. A se- 
cond and smaller nerve, of the same destination, called the lesser 
Splanchnic Nerve, arises lower down, from two or three of the 
lowermost dorsal ganglions, and penetrates separately into the 
cavity of the abdomen: it then generally divides into two 
branches, one of which unites to the great splanchnic nerve, and 
the other proceeds to the renal plexus soon to be described. 

As soon as the great splanchnic nerve has entered the abdo- 
men, it divides into many branches, which commonly form small 
ganglions on each side of the coeliac artery, but above it. These 
ganglions are generally contiguous : but sometimes they are at 
a small distance from each other, and united by nerves. They 
are, however, commonly spoken of as one, and called the Semi- 
lunar Ganglion. They are of irregular forms, and very differ- 
ent from each other in size, as well as form. Those formed by 
the splanchnic nerve on one side are sometimes different from 
those on the other. 

From this assemblage of ganglions proceed many small 
nerves, which are woven together so as to form a network 
denominated the Solar Plexus. 

This plexus is situated anterior to the spine and the crura of 
the diaphragm, behind the stomach and above the pancreas ; and 
is extended upon the coeliac and superior mesenteric arteries. 
Some ramifications from the par vagum and the phrenic also 
join it. 

The lower part of the solar plexus, which surrounds more im- 
mediately the coeliac artery, is termed the Coeliac Plexus. From 
it networks of nerves extend upon the great branches of the 
artery to the organs to which they go. 

They extend to the stomach, (although it is supplied by the 
par vagum,) along the superior coronary or gastric branch of 
the coeliac; and the fibres in their composition being spread upon 
the coats of the stomach, unite with the branches of the par 
vagum, which are also spread upon them. 



COELIAC, MESENTERIC, AND RENAL PLEXUSES. 4Q7 

A similar network, denominated the Hepatic Plexus, extends 
upon the Hepatic Artery, and from it to the Vena Portarum ; and 
accompanies those vessels into the substance of the liver. It 
also sends branches to the biliary duct and gall-bladder ; to the 
stomach by the arteria gastrica dextra; and to the omentum.